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PhysicsFinal

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Test sobre PhysicsFinal, creado por Alina Targaryen el 05/01/2017.
Alina Targaryen
Test por Alina Targaryen , actualizado hace más de 1 año
Alina Targaryen
Creado por Alina Targaryen hace casi 8 años
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Resumen del Recurso

Pregunta 1

Pregunta
A baseball of mass m is thrown upward with some initial speed. A gravitational force is exerted on the ball
Respuesta
  • At all points in its motion
  • At all points in its motion except at the highest point
  • At no points in its motion
  • Only at downward part of its direction

Pregunta 2

Pregunta
The kinetic friction will always be
Respuesta
  • Less than static friction
  • Greater than static friction
  • Equal to the static friction
  • Negative

Pregunta 3

Pregunta
The unit of coefficient of friction in SI system is
Respuesta
  • Newton
  • Dyne
  • None of these
  • No unit

Pregunta 4

Pregunta
Whenever a constant force is applied on a body then it will move with __________.
Respuesta
  • Constant Speed
  • Constant Velocity
  • Constant Acceleration
  • None of them

Pregunta 5

Pregunta
Power is a __________.
Respuesta
  • Scalar Quantity
  • Vector Quantity
  • None of these
  • Rate of force

Pregunta 6

Pregunta
The dot product of force and velocity is called __________.
Respuesta
  • Work
  • Power
  • Energy
  • Momentum

Pregunta 7

Pregunta
When the force and displacement are perpendicular to each other, then work is __________.
Respuesta
  • zero
  • Maximum
  • None of these
  • Depends on force magnitude

Pregunta 8

Pregunta
Centripetal acceleration and tangential acceleration are always __________
Respuesta
  • Parallel to Each other, but in opposite direction
  • Perpendicular to each other
  • None of these
  • Parallel to Each other, but in the same direction

Pregunta 9

Pregunta
The dimensions of angular momentum are __________.
Respuesta
  • MLT-1
  • MLT-2
  • ML2T-2
  • ML2T-1

Pregunta 10

Pregunta
The moment of inertia of a wheel about its axle does not depend upon its:
Respuesta
  • Diameter
  • Mass
  • distribution of mass
  • speed of rotation

Pregunta 11

Pregunta
Two waves have the same frequency. Which wave characteristic must also be identical for both waves?
Respuesta
  • Phase
  • Amplitude
  • Intensity
  • Period

Pregunta 12

Pregunta
A mechanical wave generally does NOT
Respuesta
  • move the medium from one place to another
  • move through a medium
  • move through solids
  • disturb the medium

Pregunta 13

Pregunta
The moment of inertia of a body depends on
Respuesta
  • the angular velocity
  • the angular acceleration
  • the mass distribution
  • the torque acting on the body

Pregunta 14

Pregunta
A skater can spin faster by pulling in her arms closer to her body or spin slower by spreading her arms out from her body. This is due to
Respuesta
  • Conservation of momentum
  • Conservation of energy
  • Newton’s third law
  • Conservation of angular momentum

Pregunta 15

Pregunta
The SI units for Coulomb constant ke are:
Respuesta
  • N·m2/C2
  • N·m/C
  • N·m/C2
  • m2/C2
  • No correct answer

Pregunta 16

Pregunta
The electric field vector E can be expressed as:
Respuesta
  • E=Fe/q
  • E=Fe/q2
  • E=Fe·q
  • E=Fe·q2
  • No correct answer

Pregunta 17

Pregunta
Which statements are correct?
Respuesta
  • Charges of opposite sign attract one another and charges of the same sign repel one another. Total charge in an isolated system is conserved. Charge is quantized.
  • Charges of opposite sign repel one another and charges of the same sign attract one another. Total charge in an isolated system is conserved. Charge is quantized.
  • Charges of opposite sign attract one another and charges of the same sign repel one another. Total charge in an isolated system is not conserved. Charge is quantized.
  • Charges of opposite sign repel one another and charges of the same sign attract one another. Total charge in an isolated system is ot conserved. Charge is not quantized.
  • No correct answer

Pregunta 18

Pregunta
Which statements are correct?
Respuesta
  • Conductors are materials in which electrons move freely. Insulators are materials in which electrons do not move freely.
  • Insulators are materials in which electrons move freely. Conductors are materials in which electrons do not move freely.
  • Conductors are materials in which electrons don’t move freely. Insulators are materials in which electrons move freely.
  • All answers are correct
  • No correct answer

Pregunta 19

Pregunta
If the electric field is uniform and makes an angle θ with the normal to a surface of area A, the electric flux through the surface is:
Respuesta
  • ΦE=EAcosθ
  • ΦE=EAsinθ
  • ΦE=Acosθsinθ
  • ΦE=Ecosθ
  • No correct answer

Pregunta 20

Pregunta
Gauss’s law says that the net electric flux ΦE through any closed gaussian surface is equal to:
Respuesta
  • ΦE=qin/ε0
  • ΦE=qin·ε0
  • ΦE= ε0/qin
  • ΦE=qinqout/ε0
  • No correct answer

Pregunta 21

Pregunta
A conductor in electrostatic equilibrium has the following properties:
Respuesta
  • 1. The electric field is zero everywhere inside the conductor. 2. Any net charge on the conductor resides entirely on its surface. 3. The electric field just outside the conductor is perpendicular to its surface and has a magnitude σ/ε0, where σ is the surface charge density at that point. 4. On an irregularly shaped conductor, the surface charge density is greatest where the radius of curvature of the surface is the smallest.
  • 1. The electric field is zero everywhere inside the conductor. 2. Any net charge on the conductor resides partially on its surface, partially inside the conductor. 3. The electric field just outside the conductor is parallel to its surface and has a magnitude σ/ε0, where σ is the surface charge density at that point. 4. On an irregularly shaped conductor, the surface charge density is greatest where the radius of curvature of the surface is the smallest.
  • 1. The electric field is non zero everywhere inside the conductor. 2. Any net charge on the conductor resides entirely on its surface. 3. The electric field just outside the conductor is perpendicular to its surface and has a magnitude σ/ε0, where σ is the surface charge density at that point. 4. On an irregularly shaped conductor, the surface charge density is greatest where the radius of curvature of the surface is the biggest.
  • 1. The electric field is zero everywhere inside the conductor. 2. Any net charge on the conductor resides entirely inside the conductor. 3. The electric field just outside the conductor is perpendicular to its surface and has a magnitude σ/ε0, where σ is the surface charge density at that point. 4. On an irregularly shaped conductor, the surface charge density is smallest where the radius of curvature of the surface is the smallest.
  • No correct answer

Pregunta 22

Pregunta
The potential difference between two points A and B in a uniform electric field E, where s (d=|s|) is a vector that points from A to B and is parallel to E is:
Respuesta
  • ∆V=-Ed
  • ∆V=0
  • ∆V=Ed
  • ∆V=-Edsinθ
  • No correct answer

Pregunta 23

Pregunta
Which statements are correct?
Respuesta
  • An equipotential surface is one on which all points are at the same electric potential. Equipotential surfaces are perpendicular to electric field lines.
  • An equipotential surface is one on which all points are at the same electric potential. Equipotential surfaces are parallel to electric field lines.
  • An equipotential surface is one on which all points are not at the same electric potential. Equipotential surfaces are perpendicular to electric field lines.
  • An equipotential surface is one on which all points are at the same electric potential. Equipotential surfaces are perpendicular to gravitation field lines.
  • No correct answer

Pregunta 24

Pregunta
The SI unit of capacitance is:
Respuesta
  • C/V
  • V/C
  • C/V2
  • C/V·m
  • No correct answer

Pregunta 25

Pregunta
The equivalent capacitance of a parallel combination of capacitors is:
Respuesta
  • Ceq=C1+C2+C3+...
  • 1/Ceq=1/C1+1/C2+1/C3+...
  • Ceq=C1=C2=C3=...
  • Ceq=C1·C2·C3·...
  • No correct answer

Pregunta 26

Pregunta
If two or more capacitors are connected in series, the equivalent capacitance of the series combination is given by:
Respuesta
  • Ceq=C1+C2+C3+...
  • 1/Ceq=1/C1+1/C2+1/C3+...
  • Ceq=C1=C2=C3=...
  • Ceq=C1·C2·C3·...
  • No correct answer

Pregunta 27

Pregunta
The electric dipole moment p of an electric dipole has a magnitude:
Respuesta
  • p=2aQ
  • p=Q
  • p=Q2
  • p=-2aQ
  • No correct answer

Pregunta 28

Pregunta
The torque acting on an electric dipole in a uniform electric field E is:
Respuesta
  • τ=pxE
  • τ=p·E
  • τ=p/E
  • τ=qpxE
  • No correct answer

Pregunta 29

Pregunta
The potential energy of the system of an electric dipole in a uniform external electric field E is:
Respuesta
  • U=- p·E
  • U= pxE
  • U= p·E
  • No correct answer
  • U= p/E

Pregunta 30

Pregunta
The average current in a conductor is related to the motion of the charge carriers through the relationship:
Respuesta
  • Iav=nqvdA
  • Iav=nqvd
  • Iav=qvdA
  • Iav=nq/vdA
  • No correct answer

Pregunta 31

Pregunta
The magnitude of the current density J in a conductor is:
Respuesta
  • J=I/A
  • J=IA
  • J=IA2
  • J=I2/A
  • No correct answer

Pregunta 32

Pregunta
Ohm’s law in the differential form is:
Respuesta
  • J=σE
  • I=U/R
  • I=R/U
  • J=σ/E
  • No correct answer

Pregunta 33

Pregunta
Ohm’s law in the integral form is:
Respuesta
  • J=σE
  • I=U/R
  • I=R/U
  • J=σ/E
  • No correct answer

Pregunta 34

Pregunta
The resistance R of a conductor is defined as:
Respuesta
  • R=∆V/I
  • R=σE
  • R=∆V·I
  • R=I/∆V
  • No correct answer

Pregunta 35

Pregunta
The power supplied to the element, is:
Respuesta
  • P=I∆V
  • P=I/∆V
  • P=I2∆V
  • P=I∆V2
  • No correct answer

Pregunta 36

Pregunta
The power delivered to a resistor can be defined as:
Respuesta
  • P=I2R
  • P=IR
  • P=IR2
  • P=I2/R
  • No correct answer

Pregunta 37

Pregunta
The equivalent resistance of a set of resistors connected in series is:
Respuesta
  • Req=R1+R2+R3+...
  • 1/Req=1/R1+1/R2+1/R3+...
  • Req=1/(R1+R2+R3+...)
  • Req=R1+R2+R3+...R4
  • No correct answer

Pregunta 38

Pregunta
Circuits involving more than one loop are conveniently analyzed with the use of Kirchhoff’s rules:
Respuesta
  • 1. The sum of the currents entering any junction in an electric circuit must equal the sum of the currents leaving that junction. 2. The sum of the potential differences across all elements around any circuit loop must be zero.
  • 1. The product of the currents entering any junction in an electric circuit must equal the sum of the currents leaving that junction. 2. The sum of the potential differences across all elements around any circuit loop must be constant.
  • 1. The sum of the currents at any circuit loop must be zero. 2. The sum of the potential differences across all elements around any circuit loop must be zero.
  • 1. The sum of the currents entering any junction in an electric circuit must equal the sum of the currents leaving that junction. 2. The product of the potential differences across all elements around any circuit loop must be zero.
  • No correct answer

Pregunta 39

Pregunta
Two objects, with different sizes, masses, and temperatures, are placed in thermal contact. Energy travels
Respuesta
  • From the larger object to the smaller object,
  • From the object with more mass to the one with less,
  • From the object at higher temperature to the object at lower temperature,
  • Energy doesn’t travel,
  • From the object at lower temperature to the object at higher temperature,

Pregunta 40

Pregunta
On a day when the temperature reaches 50°F, what is the temperature in degrees Celsius and in kelvins?
Respuesta
  • 50 C, 323 K,
  • 40 C, 313 K,
  • 30 C, 303 K,
  • 20 C, 293 K,
  • 10 C, 283 K.

Pregunta 41

Pregunta
A helium-filled rubber balloon is left in a car on a cold winter night. Compared to its size when it was in the warm car the afternoon before, the size the next morning is
Respuesta
  • Larger
  • Smaller
  • Unchanged

Pregunta 42

Pregunta
The first law of thermodynamics can be given as ________.
Respuesta
  • for any spontaneous process, the entropy of the universe increases
  • the entropy of a pure crystalline substance at absolute zero is zero
  • ΔS = Q/T at constant temperature
  • ΔE = Q + W

Pregunta 43

Pregunta
The second law of thermodynamics can be given as __________
Respuesta
  • for any spontaneous process, the entropy of the universe increases
  • the entropy of a pure crystalline substance at absolute zero is zero
  • ΔS = Q/T at constant temperature
  • ΔE = Q + W

Pregunta 44

Pregunta
Which of the following is not a state function?
Respuesta
  • Pressure
  • Volume
  • Temperature
  • Mole

Pregunta 45

Pregunta
Two containers hold an ideal gas at the same temperature and pressure. Both containers hold the same type of gas but container B has twice the volume of container A. The average translational kinetic energy per molecule in container B is
Respuesta
  • twice that for container A
  • the same as that for container A
  • half that for container A
  • impossible to determine.

Pregunta 46

Pregunta
Two containers hold an ideal gas at the same temperature and pressure. Both containers hold the same type of gas but container B has twice the volume of container A. The internal energy of the gas in container B is
Respuesta
  • twice that for container A
  • the same as that for container A
  • half that for container A
  • impossible to determine

Pregunta 47

Pregunta
Two containers hold an ideal gas at the same temperature and pressure. Both containers hold the same type of gas but container B has twice the volume of container A. The rms speed of the gas molecules in container B is
Respuesta
  • twice that for container A
  • the same as that for container A
  • half that for container A
  • impossible to determine

Pregunta 48

Pregunta
How does the internal energy of an ideal gas change as it follows path i->f in figure?
Image:
e755a325-a5c6-4ead-bd44-c251288dd456 (image/png)
Respuesta
  • Eint increases
  • Eint decreases
  • Eint stays the same
  • There is not enough information to determine how Eint changes

Pregunta 49

Pregunta
How does the internal energy of an ideal gas as it follows path f->f1 along the isotherm labeled T + deltaT in figure ?
Image:
2bbd4276-c6ce-470d-8fb2-90b2b06779b6 (image/png)
Respuesta
  • increases
  • decreases
  • stays the same
  • There is not enough information to determine how changes

Pregunta 50

Pregunta
Latent heat is
Respuesta
  • the heat released or absorbed by a thermodynamic system during a process that occurs without a change in temperature
  • the amount of energy needed to raise the temperature of sample by 1°C
  • the heat capacity per unit mass
  • the amount of heat required to change a unit mass of a substance by one degree in temperature
  • amount of energy necessary to raise the temperature of 1 g of water from 14.5°C to 15.5°C.

Pregunta 51

Pregunta
Adiabatic process is
Respuesta
  • process that occurs at constant volume
  • process that occurs at constant temperature
  • process that occurs at constant pressure
  • process in which the net heat transfer between the system and its surroundings is zero
  • process that obeys the relation: pVn=C

Pregunta 52

Pregunta
A diatomic gas molecule has ... degrees of freedom
Respuesta
  • 3
  • 5
  • 6
  • 7
  • more

Pregunta 53

Pregunta
Energy may be transferred by
Respuesta
  • work
  • conduction
  • convection
  • radiation
  • all answers are correct

Pregunta 54

Pregunta
The molar specific heat of a gas is measured at constant volume and found to be 11R/2. The gas is most likely to be
Respuesta
  • monatomic
  • diatomic
  • monatomic or diatomic, depends on the conditions
  • polyatomic
  • all answers are incorrect

Pregunta 55

Pregunta
Parallel wires carrying currents I1 and I2 respectively
Respuesta
  • repel if they are directed opposite
  • will attract if they are directed opposite
  • will not interact

Pregunta 56

Pregunta
What are the opposite ends of a magnet called?
Respuesta
  • Its terminals
  • Its north and south poles
  • Its magnetic fields
  • Its electromagnetic poles

Pregunta 57

Pregunta
How are electrical charges and magnetic poles similar?
Respuesta
  • Unlike attract and the same type repel
  • Both are plus and minus
  • Magnetic poles attract electrons
  • Both change positive to negative charges

Pregunta 58

Pregunta
How can you show that electricity creates a magnetic field?
Respuesta
  • Use a compass near a wire with current flowing through it
  • Only magnets create magnetic fields
  • Move a wire through a magnetic field
  • Connect a battery to the magnetic field

Pregunta 59

Pregunta
How can you make an electromagnet?
Respuesta
  • Attach a natural magnet to a battery
  • Run current through a wire wrapped around an iron rod
  • Line up the N and S poles of a magnet with an electric wire
  • Wrap a magnet around a piece of wire with current flowing through it

Pregunta 60

Pregunta
What happens when you turn off the current in an electromagnet?
Respuesta
  • The magnetism is turned off
  • The current keeps flowing because of the magnetic force
  • The electromagnet reverses its polarity
  • The electromagnet becomes a generator

Pregunta 61

Pregunta
How can you create electricity with a magnet?
Respuesta
  • Attach a magnet to a battery
  • By putting a current through a wire around a magnet
  • By moving a wire through a magnetic field
  • You can't, because only friction on electric charges creates electricity

Pregunta 62

Pregunta
Can you create electricity with a magnet?
Respuesta
  • No, because only friction on electric charges or batteries create electricity
  • Yes, by moving a wire through a magnetic field
  • Yes, by putting a current through a wire around a magnet
  • Yes because magnets use electricity to stay effective

Pregunta 63

Pregunta
The geomagnetic field
Respuesta
  • makes the Earth like a huge horseshoe magnet
  • runs exactly through the geographic poles
  • makes a compass work
  • makes an electromagnet work

Pregunta 64

Pregunta
A material that can be permanently magnetized is generally said to be
Respuesta
  • magnetic
  • electromagnetic
  • permanently magnetic
  • ferromagnetic

Pregunta 65

Pregunta
The magnetic flux around a straight current-carrying wire
Respuesta
  • gets stronger with increasing distance from the wire
  • is strongest near the wire
  • does not vary in strength with distance from the wire
  • consists of straight lines parallel to the wire

Pregunta 66

Pregunta
The gauss is a unit of
Respuesta
  • overall magnetic field strength
  • ampere-turns
  • magnetic flux density
  • magnetic power

Pregunta 67

Pregunta
If a wire coil has 10 turns and carries 500 mA of current, what is the magnetomotive force in ampere-turns?
Respuesta
  • 5,000
  • 50
  • 5.0
  • 0.02

Pregunta 68

Pregunta
Which of the following is not generally observed in a geomagnetic storm?
Respuesta
  • Charged particles streaming out from the Sun
  • Fluctuations in the Earth’s magnetic field
  • Disruption of electrical power transmission
  • Disruption of microwave propagation

Pregunta 69

Pregunta
A device that reverses magnetic field polarity to keep a dc motor rotating is
Respuesta
  • a solenoid
  • an armature coil
  • a commutator
  • a field coil

Pregunta 70

Pregunta
When the speed at which a conductor is moved through a magnetic field is increased, the induced voltage
Respuesta
  • increases
  • decreases
  • remains constant
  • reaches zero

Pregunta 71

Pregunta
The induced voltage across a coil with 250 turns that is located in a magnetic field that is changing at a rate of 8 Wb/s is
Respuesta
  • 1,000 V
  • 2,000 V
  • 31.25 V
  • 3.125 V

Pregunta 72

Pregunta
For a given wirewound core, an increase in current through the coil
Respuesta
  • reverses the flux lines
  • decreases the flux density
  • increases the flux density
  • causes no change in flux density

Pregunta 73

Pregunta
If the cross-sectional area of a magnetic field increases, but the flux remains the same, the flux density
Respuesta
  • Increases
  • decreases
  • remains the same
  • doubles

Pregunta 74

Pregunta
When the current through the coil of an electromagnet reverses,
Respuesta
  • direction of the magnetic field reverses
  • direction of the magnetic field remains unchanged
  • magnetic field expands
  • magnetic field collapses

Pregunta 75

Pregunta
What is the reluctance of a material that has a length of 0.07 m, a cross-sectional area of 0.014 m2, and a permeability of 4,500 Wb/At × m?
Respuesta
  • 1111 At/Wb
  • 111 At/Wb
  • 11 At/Wb
  • 1 At/Wb

Pregunta 76

Pregunta
A coil of wire is placed in a changing magnetic field. If the number of turns in the coil is decreased, the voltage induced across the coil will
Respuesta
  • increase
  • decrease
  • remain constant
  • be excessive

Pregunta 77

Pregunta
What is the flux density when the flux is 5.5 Wb and the cross-sectional area is 6 × 10–3 m2?
Respuesta
  • 91.7 µT
  • 917 µT
  • 91 T
  • 9.7 T

Pregunta 78

Pregunta
If the steel disk in a crankshaft position sensor has stopped with the tab in the magnet's air gap, the induced voltage
Respuesta
  • increases
  • decreases
  • is zero
  • will remain constant

Pregunta 79

Pregunta
What is the flux density in a magnetic field in which the flux in 0.1 m2 is 600 Wb?
Respuesta
  • 6,000 µT
  • 600 µT
  • 600 T
  • 6 T

Pregunta 80

Pregunta
A parallel-plate capacitor with air between the plates has an area A=2.00·104 m2 and a plate separation d=1.00 mm. Find its capacitance.
Respuesta
  • C=1.77 pF
  • C=1.77 F
  • C=1.77 mF
  • C=1.77 nF
  • No correct answer

Pregunta 81

Pregunta
Find the equivalent capacitance between a and b for the combination of capacitors shown in Figure. All capacitances are in microfarads.
Image:
4b82f230-5f47-48f7-bc32-9002b58f1d6a (image/png)
Respuesta
  • 6.0 μF
  • 6.0 F
  • 5.0 μF
  • 6.0 nF
  • No correct answer

Pregunta 82

Pregunta
A parallel-plate capacitor has plates of dimensions 2.0 cm by 3.0 cm separated by a 1.0-mm thickness of paper. Find its capacitance (k = 3.7, ε0=8.85·10-12 C2/N·m2).
Respuesta
  • 20 pF
  • 20 F
  • 40 pF
  • 60 pF

Pregunta 83

Pregunta
Find the electric flux Φe though the spherical surface, covers the point-like charges q1=5 nC and q2=-2 nC. (ε0=8.85·10-12 C2/N·m2)
Respuesta
  • Φe=339 N·m2/C
  • Φe=0.339 N·m2/C
  • Φe=339 N/C
  • Φe=339 N·m2
  • No correct answer

Pregunta 84

Pregunta
Find the attractive force F between nuclei of hydrogen atom and electron. Radius of hydrogen atom is r=0.5·10-10 m; modules charge of nuclei are equal and opposite to charge sign of electron (ε0=8.85·10-12 C2/N·m2).
Respuesta
  • F=92.3·10-9 N
  • F=92.3 N
  • F=92.3·10-9 N/m2
  • F=923·10-9 N
  • No correct answer

Pregunta 85

Pregunta
Two point-like charges in air (ε=1) at the distance r1=20 sm from each other interact with some force. At what distance r2 one needs to place this charges in oil (ε2=5) to get the same force of interaction?
Respuesta
  • r2=8.94 sm
  • r2=8.94 m
  • r2=8.94·103 m
  • r2=8.94·10-3 m
  • No correct answer

Pregunta 86

Pregunta
The electron and proton of a hydrogen atom are separated (on the average) by a distance of approximately 5.3·10-11 m. Find the magnitudes of the electric force between the two particles. (ke=8.99·109 N·m2/C2)
Respuesta
  • 8.2·10-8 N
  • 8.2 N
  • 8.2·10-9 N
  • 8.2·109 N
  • No correct answer

Pregunta 87

Pregunta
Calculate the resistance of an aluminum cylinder that has a length of 10.0 cm and a cross-sectional area of 2.00·10-4 m2 (ρ=2.82·10-8 Ω·m).
Respuesta
  • R=1.4·10-5 Ω
  • R=1.4·10-3 Ω
  • R=1.4 Ω
  • R=1.4·105 Ω
  • No correct answer

Pregunta 88

Pregunta
Calculate the resistance of an glass cylinder that has a length of 10.0 cm and a cross-sectional area of 2.00·10-4 m2 (ρ=3·1010 Ω·m).
Respuesta
  • R=1.5·10^13 Ω
  • R=1.5·10^-13 Ω
  • R=1.5·10^3 Ω
  • No correct answer

Pregunta 89

Pregunta
Calculate the resistance per unit length of a 22-gauge Nichrome wire, which has a radius of 0.321 mm (The resistivity of Nichrome is 1.5·10-6 Ω·m).
Respuesta
  • 4.6 Ω/m
  • 4.6 Ω
  • 4.6 Ω·m
  • 4.6·10-3 Ω/m
  • No correct answer

Pregunta 90

Pregunta
If a potential difference of 10 V is maintained across a 1.0-m length of the Nichrome wire with resistance 4.6 Ω, what is the current in the wire?
Respuesta
  • 2.2 A
  • 0.46 A
  • 2.2·10-3 A
  • 0.46·103 A
  • No correct answer

Pregunta 91

Pregunta
An electric heater is constructed by applying a potential difference of 120 V to a Nichrome wire that has a total resistance of 8.00 Ω. Find the current carried by the wire.
Respuesta
  • 15 A
  • 0.06 A
  • 15·10-3 A
  • 0.06·10-3 A
  • No correct answer

Pregunta 92

Pregunta
An electric heater is constructed by applying a potential difference of 120 V to a Nichrome wire that has a total resistance of 8.00 Ω. Find the power rating of the heater.
Respuesta
  • 1.8 kW
  • 1.8 W
  • 120 W
  • 0.1 kW
  • No correct answer

Pregunta 93

Pregunta
A battery has an emf of 12.0 V and an internal resistance of 0.05 Ω. Its terminals are connected to a load resistance of 3.00 Ω. Find the terminal voltage of the battery.
Respuesta
  • 11.8 V
  • 8.07 V
  • 11.95 A
  • All answers are correct
  • No correct answer

Pregunta 94

Pregunta
Calculate the power delivered to the load resistor, if the current in the circuit is 3.93 A, the load resistance is 3.00 Ω.
Respuesta
  • 46.3 W
  • 11.79 W
  • 35.37 W
  • All answers are correct
  • No correct answer

Pregunta 95

Pregunta
Calculate the power delivered to the internal resistance of the battery, if the current in the circuit is 3.93 A, the internal resistance of 0.05 Ω.
Respuesta
  • 0.772 W
  • 0.1965 W
  • 0.01 W
  • All answers are correct
  • No correct answer

Pregunta 96

Pregunta
Four resistors are connected as shown in Figure. Find the equivalent resistance between points a and b
Image:
4900d6d6-e320-4af7-aeb8-6c88c52b6158 (image/png)
Respuesta
  • 12 Ω
  • 2.7 Ω
  • 5.37 Ω
  • All answers are correct
  • No correct answer

Pregunta 97

Pregunta
Four resistors are connected as shown in Figure. Find the equivalent resistance between points b and c.
Image:
db9687d7-2c5a-4de1-b4c9-e5ea816de026 (image/png)
Respuesta
  • 2 Ω
  • 0.5 Ω
  • 9 Ω
  • All answers are correct
  • No correct answer

Pregunta 98

Pregunta
Four resistors are connected as shown in Figure. Find the equivalent resistance between points a and c.
Image:
fff80c0b-b85b-4994-a2aa-c7e54a020e0e (image/png)
Respuesta
  • 14 Ω
  • 2.5 Ω
  • 4.7 Ω
  • 3.2 Ω
  • No correct answer

Pregunta 99

Pregunta
Three resistors are connected in parallel as shown in Figure. A potential difference of 18.0 V is maintained between points a and b. Find the current I1.
Image:
e70ad47b-8765-42ef-a63c-e973fbde9085 (image/png)
Respuesta
  • I1=6.00 A
  • I1=3.00 A
  • I1=2.00 A
  • All answers are correct
  • No correct answer

Pregunta 100

Pregunta
Three resistors are connected in parallel as shown in Figure. A potential difference of 18.0 V is maintained between points a and b. Find the current I2.
Image:
e5a347b0-f7dd-4a5c-9ec2-365ac1dc9f27 (image/png)
Respuesta
  • I1=6.00 A
  • I1=3.00 A
  • I1=2.00 A
  • All answers are correct
  • No correct answer

Pregunta 101

Pregunta
Three resistors are connected in parallel as shown in Figure. A potential difference of 18.0 V is maintained between points a and b. Find the current I3.
Image:
8d09874e-98b9-47fd-b02d-91ad3b1deee1 (image/png)
Respuesta
  • I1=6.00 A
  • I1=3.00 A
  • I1=2.00 A
  • All answers are correct
  • No correct answer

Pregunta 102

Pregunta
Three resistors are connected in parallel as shown in Figure. A potential difference of 18.0 V is maintained between points a and b. Calculate the power delivered to resistor R1.
Image:
bc99bfe1-4a1d-4a1b-b8e0-c84d3dfd4a4e (image/png)
Respuesta
  • P1=108 W
  • P1=54 W
  • P1=36 W
  • All answers are correct
  • No correct answer

Pregunta 103

Pregunta
Three resistors are connected in parallel as shown in Figure. A potential difference of 18.0 V is maintained between points a and b. Calculate the equivalent resistance of the circuit.
Image:
f01ece77-ce83-45d4-9fb1-957fc39bad3b (image/png)
Respuesta
  • Req=1.64 Ω
  • Req=0.61 Ω
  • Req=18 Ω
  • All answers are correct
  • No correct answer

Pregunta 104

Pregunta
A single-loop circuit contains two resistors and two batteries, as shown in Figure. (Neglect the internal resistances of the batteries.) Find the current in the circuit.
Respuesta
  • I=-0.33 A
  • I=0.33 A
  • I=1 A
  • I=-3 A
  • No correct answer

Pregunta 105

Pregunta
Consider three point charges located at the corners of a right triangle as shown in Figure, where q1 = q3 = 5.0 μC, q2 =-2.0 μC, and a = 0.10 m. Find the resultant force exerted on q3
Image:
1503608f-8a30-42d7-9bde-7858d0416dac (image/png)
Respuesta
  • F3=(-1.1i+7.9j)N
  • F3=(7.9i-1.1j)N
  • F3=(1.1i-7.9j)N
  • F3=(1.1i+7.9j)N
  • No correct answer

Pregunta 106

Pregunta
An electric dipole is defined as a positive charge q and a negative charge -q separated by a distance 2a. For the dipole shown in Figure, find the electric field E at P due to the dipole, where P is a distance y » a from the origin.
Respuesta
  • E≈(k * 2qa)/y^3
  • E≈(k*2q)/a^3
  • E≈(k*2)/y^5
  • E≈2qa/y^3
  • No correct answer

Pregunta 107

Pregunta
A rod of length l has a uniform positive charge per unit length λ and a total charge Q. Calculate the electric field at a point P that is located along the long axis of the rod and a distance a from one end.
Image:
7e71d95c-4698-4b9b-92af-0102643ef1e1 (image/png)
Respuesta
  • E=(k* Q)/(a(l+a))
  • E=(k*Q)/(l+a)
  • E=(k*Q)/al
  • E=k/(a(l+a))
  • No correct answer

Pregunta 108

Pregunta
Calculate the ratio of the electrostatic to gravitational interaction forces between two electrons, between two protons. At what value of the specific charge q/m of a particle would these forces become equal (in their absolute values) in the case of interaction of identical particles? (γ=6.67·10-11 m3/(kg·s2), me=9·10-31kg, mp=1·10-27kg, ke=8.99·109 N·m2/ C2)
Respuesta
  • 4·1042 (for electrons); 1·1036 (for proton); q/m=0.86·10-10 C/kg
  • 4·1042 (for proton); 1·1036 (for electrons); q/m=0.86·10-10 C/kg
  • 4·1045 (for proton); 1·1038 (for electrons); q/m=0.86·10-13 C/kg
  • 4·1043 (for electrons); 1·1035 (for proton); q/m=0.86·10-11 C/kg
  • No correct answer

Pregunta 109

Pregunta
Find the currents I1, I2, and I3 in the circuit shown in Figure.
Image:
ade07d5a-ec86-44ea-a2f5-6cace31faf27 (image/png)
Respuesta
  • I1=2 A, I2=-3 A, I3=-1 A
  • I1=-2 A, I2=3 A, I3=1 A
  • I1=2 A, I2=-3 A, I3=-5 A
  • I1=3 A, I2=2 A, I3=1 A
  • No correct answer

Pregunta 110

Pregunta
The water (H2O) molecule has an electric dipole moment of 6.3·10-30 C·m. A sample contains 1021 water molecules, with the dipole moments all oriented in the direction of an electric field of magnitude 2.5·105 N/C. How much work is required to rotate the dipoles from this orientation (θ=0°) to one in which all the moments are perpendicular to the field (θ=90°)?
Respuesta
  • 1.6·10-24 J
  • 1.6·10-3 J
  • -1.6·10-3 J
  • 1.6·10-25 J
  • No correct answer

Pregunta 111

Pregunta
A ball is thrown upward. While the ball is in free fall, does its acceleration
Respuesta
  • Increases
  • Decreases
  • Increases and then decreases
  • Decreases and then increases
  • Remain constant

Pregunta 112

Pregunta
After a ball is thrown upward and is in the air, its speed in all path
Respuesta
  • Increases
  • Decreases
  • Increases and then decreases
  • Decreases and then increases
  • Remain the same

Pregunta 113

Pregunta
If vector B is added to vector A, which two of the following choices must be true in order for the resultant vector to be equal to zero?
Respuesta
  • A and B are parallel in the same direction and have same magnitude
  • A and B are parallel in opposite directions, but have same magnitude
  • A and B have the same magnitude
  • A and B are perpendicular but have same magnitude
  • None of them is right

Pregunta 114

Pregunta
A car moves along y-axes. In the figure, velocity of the car as a function of time is shown in three parts (I, II, III). Which statement is ALWAYS true?
Image:
7cfb444c-ab1d-4e26-aa8c-1d41d94d6c74 (image/png)
Respuesta
  • Velocity is constant in part II
  • A car drives backward in part I
  • Velocity is negative in part III
  • Velocity is negative in part I

Pregunta 115

Pregunta
What is the cross product of two vectors A and B, if the angle between them is 30 degree, and magnitudes are |A|=4, |B|=2
Respuesta
  • 5.6
  • 4
  • 0
  • 8
  • 2.5

Pregunta 116

Pregunta
When a box rests on the floor, it is acted upon by the gravitational and the _________________ force.
Respuesta
  • Centrifugal
  • Acceleration
  • Normal
  • Inertia
  • Friction

Pregunta 117

Pregunta
Motion is produced by
Respuesta
  • all forces
  • unbalanced forces
  • balanced forces
  • the absence of force
  • none of them

Pregunta 118

Pregunta
Force is that agent which produces or tends to produce the __________.
Respuesta
  • Speed in the body
  • Acceleration in the body
  • Constant velocity in the body
  • Constant angular velocity in the body

Pregunta 119

Pregunta
A force of 3N acts perpendicularly to a force of 4N. Their resultant has magnitude of ______
Respuesta
  • 1N
  • 5N
  • 7N
  • 9N
  • 25N

Pregunta 120

Pregunta
In inelastic collision between the two bodies __________.
Respuesta
  • Only momentum of the system is conserved
  • Only the kinetic Energy of the system is conserved
  • Both the kinetic Energy and Momentum of the system remain the same
  • Total energy is not conserved

Pregunta 121

Pregunta
Work done by a grass cutter is maximum when he pulls it __________.
Respuesta
  • Making an angle 450 with the floor
  • Making an angle 900 with the floor
  • Along a line parallel to the floor
  • Making an angle 600 with the floor

Pregunta 122

Pregunta
A man does the work if he ___________.
Respuesta
  • Goes to fifth floor of the building
  • Goes to fifth floor of the building and comes back to ground floor
  • Remain on the ground floor
  • Goes to the basement and comes back to ground floor

Pregunta 123

Pregunta
In elastic collision between the two bodies __________.
Respuesta
  • Only momentum of the system is conserved
  • Only the kinetic Energy of the system is conserved
  • Both the kinetic Energy and Momentum of the system remain the same
  • Total energy is not conserved

Pregunta 124

Pregunta
When the force and displacement are parallel to each other, then work is __________.
Respuesta
  • Minimum
  • Maximum
  • None of these
  • Depends on force magnitude

Pregunta 125

Pregunta
In rotational motion, the quantity, which plays the same role as the inertial mass in linear motion, is called ___________.
Respuesta
  • Inertia
  • Angular momentum
  • Moment of inertia
  • Torque
  • Center of mass

Pregunta 126

Pregunta
Four identical particles, each with mass m, are arranged in the x, y plane as shown. They are connected by light sticks to form a rigid body. If m = 2.0 kg and a = 1.0 m, the rotational inertia of this array about the y-axis is:
Image:
22d70f92-c909-4aad-8db8-96ac9aed7637 (image/png)
Respuesta
  • 4.0 kg  m2
  • 12 kg  m2
  • 9.6 kg  m2
  • 4.8 kg  m2
  • none of these

Pregunta 127

Pregunta
Sound travels faster in
Respuesta
  • a vacuum
  • water
  • steel
  • air
  • Sound travels at about the same speed in all of the above media.

Pregunta 128

Pregunta
A woman sits on a spinning stool with her arms folded. When she extends her arms, which of the following occurs
Respuesta
  • She increases her moment of inertia, thus increasing her angular speed
  • She increases her moment of inertia, thus decreasing her angular speed.
  • She decreases her moment of inertia, thus increasing her angular speed
  • She decreases her moment of inertia, thus decreasing her angular speed
  • Her angular speed remains constant by conservation of angular momentum

Pregunta 129

Pregunta
The pressure at the surface of the ocean is 1 atm (1 x 105 Pa). At what approximate depth in the ocean water (ρ = 1025 kg/m3) would the absolute pressure be 2 atm?
Respuesta
  • 1 m
  • 5 m
  • 10 m
  • 100 m
  • 1000 m

Pregunta 130

Pregunta
A plane loop of wire consisting for the bowling ball that rotates about z-axis?
Image:
5374ead3-18ce-43f0-8316-d9ba0c035e67 (image/png)
Respuesta
  • +y
  • –y
  • +x
  • –x
  • +z
  • –z

Pregunta 131

Pregunta
A segment of steel railroad track has a length of 30.000 m when the temperature is 0.0°C. What is its length when the temperature is 40.0°C? (Average linear expansion coefficient for steel is α=11* 10-6 °C-1).
Respuesta
  • 0.013 m.
  • 30.013 m.
  • 30.130 m.
  • 30.003 m.
  • 31.013 m.

Pregunta 132

Pregunta
An ideal gas occupies a volume of 100 cm3 at 20°C and 100 Pa. Find the number of moles of gas in the container (Universal gas constant R= 8.314 J/mol*K).
Respuesta
  • 4.11 * 10-5 mol
  • 20.11 * 10-6 mol
  • 20.11 * 10-5 mol
  • 1.20 * 10-6 mol
  • 4.11 * 10-6 mol

Pregunta 133

Pregunta
The concrete sections of a certain superhighway are designed to have a length of 25.0 m. The sections are poured and cured at 10.0°C. What minimum spacing should the engineer leave between the sections to eliminate buckling if the concrete is to reach a temperature of 50.0°C? (Average linear expansion coefficient for concrete is α=12* 10-6 °C-1).
Respuesta
  • 1.20 cm
  • 1.25 cm
  • 1.35 cm
  • 25.20 cm
  • 25.40 cm

Pregunta 134

Pregunta
Just 9.00 g of water is placed in a 2.00-L pressure cooker and heated to 500°C. What is the pressure inside the container? (Molar mass of water M(H2O) = 18 g/mol, universal gas constant R= 8.314 J/mol*K ).
Respuesta
  • 16.1 Pa
  • 1.61 Pa
  • 1.61 MPa
  • 161 MPa
  • 161 Pa

Pregunta 135

Pregunta
The temperature of a silver bar rises by 10.0°C when it absorbs 1.23 J of energy by heat. The mass of the bar is 525 g. Determine the specific heat of silver.
Respuesta
  • 128 J/kg . °C
  • 234 J/kg . °C
  • 380 J/kg . °C
  • 860 J/kg . °C
  • 2 010 J/kg . °C

Pregunta 136

Pregunta
A 50.0-g sample of copper is at 25.0°C. If 1 200 J of energy is added to it by heat, what is the final temperature of the copper? (Specific heat of copper c= 387 J/kg . °C).
Respuesta
  • 50 °C
  • 62 °C
  • 77 °C
  • 87°C
  • 99 °C

Pregunta 137

Pregunta
Determine the work done on a fluid that expands from i to f as indicated in Figure.
Image:
7d411710-128e-44f8-b237-b7c1c6b7902c (image/png)
Respuesta
  • 12 MJ
  • -12 J
  • -12 MJ
  • -6 J
  • 6 MJ

Pregunta 138

Pregunta
A gas is taken through the cyclic process described in Figure. Find the net energy transferred to the system by heat during one complete cycle.
Respuesta
  • 12 kJ
  • 12 J
  • 1200 kJ
  • 4 kJ
  • 6 kJ

Pregunta 139

Pregunta
An ideal gas initially at 300 K undergoes an isobaric expansion at 2.50 kPa. If the volume increases from 1.00 m3 to and 12.5 kJ is transferred to the gas by heat, what is the change in its internal energy?
Respuesta
  • 6.5 kJ
  • 6.5 J
  • 7.5 kJ
  • 13.5 kJ
  • 25 kJ

Pregunta 140

Pregunta
A glass window pane has an area of 3.00 m2 and a thickness of 0.600 cm. If the temperature difference between its faces is 25.0°C, what is the rate of energy transfer by conduction through the window? (Thermal conductivity of glass k= 0.8 W/m* °C)
Respuesta
  • 10 W
  • 100 W
  • 100 kW
  • 1 kW
  • 10 kW

Pregunta 141

Pregunta
A cylinder contains a mixture of helium and argon gas in equilibrium at 150°C. What is the average kinetic energy for each type of gas molecule? (Boltzmann constant kB= 1.38* 10-23 J/K).
Respuesta
  • 8.76* 10-23 J
  • 8.76* 10-21 J
  • 10.8* 10-21 J
  • 10.8* 10-23 J
  • 87.6* 10-21 J

Pregunta 142

Pregunta
Calculate the change in internal energy of 3.00 mol of helium gas when its temperature is increased by 2.00 K (Universal gas constant R= 8.314 J/mol*K ).
Respuesta
  • 49.9 J
  • 4.99 J
  • 499 J
  • 748 J
  • 74.8 J

Pregunta 143

Pregunta
A 2.00-mol sample of a diatomic ideal gas expands slowly and adiabatically from a pressure of 5.00 atm and a volume of 12.0 L to a final volume of 30.0 L. What is the final pressure of the gas?
Respuesta
  • 5.33 atm
  • 4.21 atm
  • 3.39 atm
  • 2.91 atm
  • 1.39 atm

Pregunta 144

Pregunta
A 2.00-mol sample of a diatomic ideal gas expands slowly and adiabatically from a pressure of 5.00 atm and a volume of 12.0 L to a final volume of 30.0 L. What are the initial and final temperatures? (Universal gas constant R= 8.314 J/mol*K, 1 atm= 1.013* 105 Pa )
Respuesta
  • 365 K, 253 K
  • 355 K, 243 K
  • 345 K, 233 K
  • 335 K, 223 K
  • 325 K, 213 K

Pregunta 145

Pregunta
A 2.00-mol sample of a diatomic ideal gas expands slowly and adiabatically from a pressure of 5.00 atm and a volume of 12.0 L to a final volume of 30.0 L. Find Q, ΔEint, and W (Universal gas constant R= 8.314 J/mol*K).
Respuesta
  • 0 J, -4.66 kJ, 4.66 kJ
  • 0 J, 4.66 kJ, - 4.66 kJ
  • 0 J, -4.66 kJ, - 4.66 kJ
  • 0 J, 4.66 kJ, 4.66 kJ
  • 0.66 J, -4.66 kJ, - 4.66 kJ

Pregunta 146

Pregunta
A heat engine takes in 360 J of energy from a hot reservoir and performs 25.0 J of work in each cycle. Find the efficiency of the engine.
Respuesta
  • 6.94 %
  • 14.4 %
  • 23.25 %
  • 45.2 %
  • 100 %

Pregunta 147

Pregunta
A heat engine performs 200 J of work in each cycle and has an efficiency of 30.0%. For each cycle, how much energy is (a) taken in and (b) expelled by heat?
Respuesta
  • 637 J, 437 J
  • 647 J, 447 J
  • 657 J, 457 J
  • 667 J, 467 J
  • 677 J, 477 J

Pregunta 148

Pregunta
A particular heat engine has a useful power output of 5.00 kW and an efficiency of 25.0%. The engine expels 8 000 J of exhaust energy in each cycle. Find the energy taken in during each cycle
Respuesta
  • 10.7 kJ
  • 11.7 kJ
  • 12.7 kJ
  • 13.7 kJ
  • 14.7 kJ

Pregunta 149

Pregunta
The unit for permeability is
Respuesta
  • Wb/At × m
  • At/m
  • At/Wb
  • Wb

Pregunta 150

Pregunta
What is the magnetomotive force in a 75-turn coil of wire when there are 4 A of current through it?
Respuesta
  • 18.75 At
  • 30 At
  • 300 At
  • 187 At

Pregunta 151

Pregunta
The direction of a magnetic field within a magnet is
Respuesta
  • from south to north
  • from north to south
  • back to front
  • front to back

Pregunta 152

Pregunta
When the north poles of two bar magnets are brought close together, there will be
Respuesta
  • no force
  • a downward force
  • a force of attraction
  • a force of repulsion

Pregunta 153

Pregunta
The ability of a material to remain magnetized after removal of the magnetizing force is known as
Respuesta
  • permeability
  • reluctance
  • hysteresis
  • retentivity

Pregunta 154

Pregunta
The voltage induced across a certain coil is 200 mV. A 120 resistor is connected to the coil terminals. The induced current is
Respuesta
  • 1.7 mA
  • 16 mA
  • 12 mA
  • 120 mA

Pregunta 155

Pregunta
The induced voltage across a stationary conductor in a stationary magnetic field is
Respuesta
  • zero
  • reversed in polarity
  • increased
  • decreased

Pregunta 156

Pregunta
When a solenoid is activated, the force that moves the plunger is
Respuesta
  • an electromagnetic field
  • a permanent magnetic field
  • varying voltage
  • a steady current

Pregunta 157

Pregunta
What is the magnetomotive force (mmf) of a wire with 8 turns carrying three amperes of current?
Respuesta
  • 2,400 At
  • 240 At
  • 24 At
  • 2.4 At

Pregunta 158

Pregunta
If a loop in a basic dc generator suddenly begins rotating at a faster speed, the induced voltage
Respuesta
  • remains unchanged
  • reverses polarity
  • increases
  • decreases

Pregunta 159

Pregunta
If an electron moves perpendicular to the uniform magnetic field of magnitude 0.35 T with the speed equal to 4.69×106, what is the radius of its circular orbit? (me = 9.11×10-31kg)
Respuesta
  • 7.63×104
  • 7.63×10-5
  • 7.63×106
  • 0.73×10-6

Pregunta 160

Pregunta
Calculate the maximum kinetic energy of protons in a cyclotron of radius 0.50 m in a magnetic field of 0.35 T.
Respuesta
  • 1.46 KeV
  • 1.46 meV
  • 1.46 MeV
  • 0.146 eV

Pregunta 161

Pregunta
A rectangular copper strip 1.5 cm wide and 0.1 cm thick carries a current of 5 A. A 1.2 T magnetic field is applied perpendicular to the strip. Find the Hall voltage that should be produced.
Respuesta
  • 0.442 µV
  • 0.442 mV
  • 4.42 V
  • 44.2 V

Pregunta 162

Pregunta
A toroidal winding carrying a current of 5 A is wound with 300 turns/m of wire. The core is iron, which has a magnetic permeability of 5000µ0 under the given conditions. Find B inside the iron core.
Respuesta
  • 9.43×〖10〗^(-3)T
  • 9.43×〖10〗^(-2)T
  • 0.943 T
  • 9.43 T

Pregunta 163

Pregunta
Assume that a motor having coils with a resistance of 10 Ω is supplied by a voltage of 120 V. When the motor is running at its maximum speed, the back emf is 70V. Find the current in the coils when the motor is first turned on.
Respuesta
  • 10 A
  • 12 A
  • 1 A
  • 1.2 A

Pregunta 164

Pregunta
Assume that a motor having coils with a resistance of 10 Ω is supplied by a voltage of 120 V. When the motor is running at its maximum speed, the back emf is 70 V. Find the current in the coils when the motor has reached maximum speed.
Respuesta
  • 3 A
  • 4 A
  • 5 A
  • 6 A

Pregunta 165

Pregunta
Calculate the inductance of a solenoid containing 300 turns if the length of the solenoid is 25 cm and its cross-sectional area is 4 cm2.
Respuesta
  • 0.181 mH
  • 0.181 H
  • 1.81 mH
  • 1.81 H

Pregunta 166

Pregunta
Calculate the self-induced emf in the solenoid containing 300 turns if the length of the solenoid is 25 cm and the current through it is decreasing at the rate of 50 A/s.
Respuesta
  • 0.905 mV
  • 9.05 mV
  • 0.905 V
  • 9.05 V

Pregunta 167

Pregunta
Calculate the time constant of RL circuit consisting of a 30 mH inductor in series with 6 Ω resistor and 12 V battery.
Respuesta
  • 180 ms
  • 60 ms
  • 5 ms
  • 2 ms

Pregunta 168

Pregunta
Three identical capacitors connected in series. What single capacitance C is “equivalent” to this combination?
Respuesta
  • 6C
  • 3C
  • (1/6)C
  • (1/3)C
  • 2C

Pregunta 169

Pregunta
You charge parallel-plate capacitor. When you pull the plates apart to a larger separation and battery remains connected to the capacitor
Respuesta
  • Decreases
  • Remains the same
  • Alternates
  • Increases
  • Changes in an unpredictable way

Pregunta 170

Pregunta
The resonant angular frequency of series RLC circuit is
Respuesta
  • 1/(LC)1/2
  • LC
  • (LC)2
  • (LC)1/2
  • 1/(LC)

Pregunta 171

Pregunta
A wire of area 2 mm2 carries a current of 0.4mA. The average current density is
Respuesta
  • 0.02A/m2
  • 0.2 A/m2
  • 2 A/m2
  • 200 A/m2
  • 20 A/m2

Pregunta 172

Pregunta
A square loop of side 0.1m carries 2A current. The magnetic dipole moment of the loop is
Respuesta
  • 10-1 Am2
  • 2*10-2 Am2
  • 1 Am2
  • 10 Am2
  • 100 Am2

Pregunta 173

Pregunta
Current 0.5A flows in square wire loop of 10 cm side. What is magnetic dipole moment of the loop?
Respuesta
  • 50 Am2
  • 0.005 Am2
  • 0.05 Am2
  • 5 Am2
  • 0.5 Am2

Pregunta 174

Pregunta
Of the three chief kinds of magnetic materials (diamagnetic, paramagnetic and ferromagnetic), which are used to make permanent magnets?
Respuesta
  • Only paramagnetic
  • All three
  • Paramagnetic and ferromagnetic
  • Only ferromagnetic
  • Only diamagnetic

Pregunta 175

Pregunta
In a photoelectric experiment at a frequency above cut off, the stopping potential is proportional to:
Respuesta
  • The energy of the most energetic electron before it is ejected
  • The energy of the least energetic electron before it is ejected
  • The energy of the most energetic electrons after it is ejected
  • The electron potential energy at the surface of the sample
  • The energy of the least energetic electron after it is ejected

Pregunta 176

Pregunta
What is the maximal number of electrons at shell with n=3
Respuesta
  • 11
  • 18
  • 9
  • 7
  • 3

Pregunta 177

Pregunta
For the serial circuit work out the readings on the voltmeters V1 and V2 given the following values for R1=2Ohm and R2=10 Ohm, I1=1A, I2=1A
Respuesta
  • V1=1V; V2=5V;
  • V1=5V; V2=10V;
  • V1=4V; V2=1V;
  • V1=10V; V2=2V;
  • V1=2V; V2=10V;

Pregunta 178

Pregunta
What is a good insulator of electricity?
Respuesta
  • Silicon
  • Iron
  • Rubber
  • Steel
  • Salt water

Pregunta 179

Pregunta
Induction current opposes the reason causing it. It is the shortest formulation of
Respuesta
  • Einstein’s law
  • Lentz law
  • Biot-Savart law
  • Faraday’s law
  • Ampere’s law

Pregunta 180

Pregunta
Potential energy of current carrying loop with magnetic dipole moment µ=1Am2 in magnetic field B of 0.1T, when B and µ make angle 600 is
Respuesta
  • -0.05J
  • -1J
  • 1J
  • 0.5J
  • 0J

Pregunta 181

Pregunta
Paramagnetism is closely associated with
Respuesta
  • The torque
  • The force exerted by electron dipole moments on each other
  • The tendency of electron dipole moments to align with an applied magnetic field
  • The exchange force between electrons
  • The tendency of electrons dipole moments to align opposite to an applied magnetic field

Pregunta 182

Pregunta
In an electromagnetic wave E0=3*106V/m. B0 equals
Respuesta
  • 10T
  • 10-2T
  • 100T
  • 1T
  • 10-8T

Pregunta 183

Pregunta
What is an insulator of electricity?
Respuesta
  • A material that doesn’t allow the free electrons to easily travel through it.
  • A material that protects the free electrons from excess heat
  • A material that protects the free electrons from internal energy propagation
  • A material that allows the free ions to easily travel through it
  • A material that allows the free electrons to easily travel through it

Pregunta 184

Pregunta
Ohm’s law in differential form is
Respuesta
  • I={φ1-φ2±ε}/R
  • ω=γE2
  • I=V/R
  • I= ε/(R+r)
  • j=γE, where j is a current density, γ is a conductivity

Pregunta 185

Pregunta
The total number of electron states with n=3 and l=1 for an atom is:
Respuesta
  • Four
  • eight
  • two
  • ten
  • six

Pregunta 186

Pregunta
The thermal conductivity is the analog to:
Respuesta
  • Thermal expansion
  • Resistivity
  • Elasticity
  • Diffusivity
  • Viscosity

Pregunta 187

Pregunta
Resistance of metals in classical theory of electric conductivity is caused by
Respuesta
  • Collision of free electrons with dislocations or clasters
  • Collision of free electrons with impurity atoms in internodes
  • Collision of free electrons with each other
  • Collision of free electrons with vacancy defects
  • Collision of free electrons with ions of crystal structure

Pregunta 188

Pregunta
Which relation defines equipotential surface:
Respuesta
  • |E ⃗|=const
  • E ⃗(Δr) ⃗=const
  • E ⃗=const
  • φ=const
  • dφ/dz=const

Pregunta 189

Pregunta
Electric theory of dispersion was evaluated by:
Respuesta
  • Lorentz
  • Newton
  • Einstein
  • Minkovsky
  • Maxwell

Pregunta 190

Pregunta
Loop is uniformly rotating with angular velocity ω in uniform magnetic field. Loop has N coils and area of the loop is S. Rotating axis lies on loop’s plane and perpendicular to induction. What is the maximal EMF appeared in the loop:
Respuesta
  • NBS/2
  • NBS
  • NBS cos(ωt)
  • NBSω/2
  • NBSω

Pregunta 191

Pregunta
Current I=1A goes through the inductance with inductivity L=10-3H. What is the magnetic flux through inductance:
Respuesta
  • 2·10-10Wb
  • 2·10-3Wb
  • 4π·10-10Wb
  • 0.5·10-3Wb
  • 10-3Wb

Pregunta 192

Pregunta
A toaster is rated at 600W when connected to a 120V source. What current does the toaster carry?
Respuesta
  • 2A
  • 1A
  • 3A
  • 4A
  • 5A

Pregunta 193

Pregunta
Charge carries in metals are
Respuesta
  • electrons and holes
  • only electrons
  • only holes
  • positive ions
  • negative ions

Pregunta 194

Pregunta
An electrton traveling with speed v around a circle of radius r is equivalent to a current of:
Respuesta
  • evr/2
  • ev/r
  • 2πer/v
  • 2πev/r
  • ev/2πr

Pregunta 195

Pregunta
The emf inducted in an isolated circuit when the current in the circuit is changing by 10 A/s is 0.3 V. What is the self-inductance?
Respuesta
  • 3 mH
  • 3 µH
  • 30 µH
  • 30 mH
  • 30 H

Pregunta 196

Pregunta
The magnetic field for a given electromagnetic wave has Bmax = 10-6T. Emax equals
Respuesta
  • 3*102 V/m
  • 10-8 V/m
  • 5 V/m
  • 3 V/m
  • 100 V/m

Pregunta 197

Pregunta
An electromagnetic field propagates in +x direction. The electric field at a point in space is momentarily oriented in –z direction. The magnetic field at that point is momentarily oriented in
Respuesta
  • –y direction
  • +y direction
  • +z direction
  • +x direction
  • -x direction

Pregunta 198

Pregunta
In RLC circuit angular frequency of AC source rises. Inductive reactance
Respuesta
  • Remains the same
  • Increases
  • Oscillates about certain value
  • Alternates
  • Decreases

Pregunta 199

Pregunta
Magnetic flux through closed conducting loop changed from 10Wb to 5Wb in 10ms. The average EMF induced in the loop is
Respuesta
  • 50V
  • 500V
  • -5V
  • -500V

Pregunta 200

Pregunta
The magnitude of emf induced in an isolated circuit when the current in the circuit is changing by -10A/s is 0.2 V. What is the self-inductance?
Respuesta
  • 2µH
  • 20mH
  • 20µH
  • 20H
  • 2mH
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