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Physics Theory #3

Pregunta 1 de 40

1

A point source is to be used with a concave mirror to produce a beam of parallel light.The source should be placed:

Selecciona una de las siguientes respuestas posibles:

  • As close to the mirror as possible

  • At the center of curvature

  • Midway between the center of curvature and the focal point

  • Midway between the center of curvature and the mirror

  • Midway between the focal point and the mirror

Explicación

Pregunta 2 de 40

1

Light from a small region of an ordinary incandescent bulb is passed through a yellow filter and then serves as the source for a Young’s double-slit experiment. Which of the following changes would cause the interference pattern to be more closely spaced?

Selecciona una de las siguientes respuestas posibles:

  • Use slits that are closer together

  • Use a light source of lower intensity

  • Use a light source of higher intensity

  • Use a blue filter instead of a yellow filter

  • Move the light source further away from the slits

Explicación

Pregunta 3 de 40

1

In an experiment to measure the wavelength of light using a double slit, it is found that the fringes are too close together to easily count them.To spread out the fringe pattern,one could:

Selecciona una de las siguientes respuestas posibles:

  • Decrease the slit separation

  • Increase the slit separation

  • Increase the width of each slit

  • Decrease the width of each slit

  • None of these

Explicación

Pregunta 4 de 40

1

If two light waves are coherent:

Selecciona una de las siguientes respuestas posibles:

  • Their amplitudes are the same

  • Their frequencies are the same

  • Their wavelengths are the same

  • Their phase difference is constant

  • The difference in their frequencies is constant

Explicación

Pregunta 5 de 40

1

The magnitude of the momentum of a particle can never exceed:

Selecciona una de las siguientes respuestas posibles:

  • mc, where m is its mass

  • E/c, where E is its total energy

  • K/c, where K is its kinetic energy

  • None of the above, but there is an upper limit

  • None of the above; there is no upper limit

Explicación

Pregunta 6 de 40

1

The units of the Planck constant h are those of:

Selecciona una de las siguientes respuestas posibles:

  • Energy

  • Power

  • Momentum

  • Angular momentum

  • Frequency

Explicación

Pregunta 7 de 40

1

The quantization of energy, E = nhf, is not important for an ordinary pendulum because:

Selecciona una de las siguientes respuestas posibles:

  • The formula applies only to mass-spring oscillators

  • The allowed energy levels are too closely spaced

  • The allowed energy levels are too widely spaced

  • The formula applies only to atoms

  • The value of h for a pendulum is too large

Explicación

Pregunta 8 de 40

1

The wavelength of light beam B is twice the wavelength of light beam B. The energy of a photon in beam A is:

Selecciona una de las siguientes respuestas posibles:

  • Half the energy of a photon in beam B

  • One-fourth the energy of a photon in beam B

  • Equal to the energy of a photon in beam B

  • Twice the energy of a photon in beam B

  • Four times the energy of a photon in beam B

Explicación

Pregunta 9 de 40

1

Which of the following electromagnetic radiations has photons with the greatest energy?

Selecciona una de las siguientes respuestas posibles:

  • Blue light

  • Yellow light

  • X rays

  • Radio waves

  • Microwaves

Explicación

Pregunta 10 de 40

1

Which of the following electromagnetic radiations has photons with the greatest momentum:

Selecciona una de las siguientes respuestas posibles:

  • Blue light

  • X rays

  • Radio waves

  • Yellow light

Explicación

Pregunta 11 de 40

1

In a photoelectric effect experiment no electrons are ejected if the frequency of the incident light is less than A/h, where h is the Planck constant and A is:

Selecciona una de las siguientes respuestas posibles:

  • The maximum energy needed to eject the least energetic electron

  • The minimum energy needed to eject the least energetic electron

  • The maximum energy needed to eject the most energetic electron

  • The minimum energy needed to eject the most energetic electron

  • The intensity of the incident light

Explicación

Pregunta 12 de 40

1

The probability that a particle is in a given small region of space is proportional to:

Selecciona una de las siguientes respuestas posibles:

  • Its energy

  • Its momentum

  • The frequency of its wave function

  • The wavelength of its wave function

  • The square of the magnitude of its wave function

Explicación

Pregunta 13 de 40

1

Maxwell’s equations are to electric and magnetic fields as equation is to the wave function for a particle:

Selecciona una de las siguientes respuestas posibles:

  • Einstein’s

  • Fermi’s

  • Newton’s

  • Schr.odinger’s

  • Bohr’s

Explicación

Pregunta 14 de 40

1

The energy of a particle in a one-dimensional trap with zero potential energy in the interior and infinite potential energy at the walls is proportional to (n = quantum number:

Selecciona una de las siguientes respuestas posibles:

  • N

  • 1/n

  • 1/n^2

  • √n

Explicación

Pregunta 15 de 40

1

A particle is trapped in a one-dimensional well with infinite potential energy at the walls Three possible pairs of energy levels are
1) n = 3 and n = 1
2) n = 3 and n = 2
3) n = 4 and n = 3
Order these pairs according to the difference in energy, least to greatest

Selecciona una de las siguientes respuestas posibles:

  • 1, 2, 3

  • 3, 2, 1

  • 2, 3, 1

  • 1, 3, 2

  • 3, 1, 2

Explicación

Pregunta 16 de 40

1

The ground state energy of an electron in a one-dimensional trap with zero potential energy in the interior and infinite potential energy at the walls:

Selecciona una de las siguientes respuestas posibles:

  • Is zero

  • Decreases with temperature

  • Increases with temperature

  • Is independent of temperature

  • Oscillates with time

Explicación

Pregunta 17 de 40

1

The ionization energy of an atom in its ground state is:

Selecciona una de las siguientes respuestas posibles:

  • The energy required to remove the least energetic electron

  • The energy required to remove the most energetic electron

  • The energy difference between the most energetic electron and the least energetic electron

  • The same as the energy of a Kα-photon

  • The same as the excitation energy of the most energetic electron

Explicación

Pregunta 18 de 40

1

In a laser:

Selecciona una de las siguientes respuestas posibles:

  • Excited atoms are stimulated to emit photons by radiation external to the laser

  • The transitions for laser emission are directly to the ground state

  • The states which give rise to laser emission are usually very unstable states that decay rapidly

  • The state in which an atom is initially excited is never between two states that are involved in a stimulated emission

  • A minimum of two energy levels are required

Explicación

Pregunta 19 de 40

1

The relation between the disintegration constant λ and the half-life T of a radioactive substance is:

Selecciona una de las siguientes respuestas posibles:

  • λ = 2T

  • λ = 1/T

  • λ = 2/T

  • λT = ln2

  • λT = ln(1/2)

Explicación

Pregunta 20 de 40

1

In a nuclear reactor the fissionable fuel is formed into pellets rather than finely ground and the pellets are mixed with the moderator This reduces the probability of

Selecciona una de las siguientes respuestas posibles:

  • Non-fissioning absorption of neutrons

  • Loss of neutrons through the reactor container

  • Absorption of two neutrons by single fissionable nucleus

  • Loss of neutrons in the control rods

  • None of the above

Explicación

Pregunta 21 de 40

1

In a subcritical nuclear reactor:

Selecciona una de las siguientes respuestas posibles:

  • The number of fission events per unit time decreases with time

  • The number of fission events per unit time increases with time

  • Each fission event produces fewer neutrons than when the reactor is critical

  • Each fission event produces more neutrons than when the reactor is critical

  • None of the above

Explicación

Pregunta 22 de 40

1

In the normal operation of a nuclear reactor:

Selecciona una de las siguientes respuestas posibles:

  • Control rods are adjusted so the reactor is subcritical

  • Control rods are adjusted so the reactor is critical

  • The moderating fluid is drained

  • The moderating fluid is continually recycled

  • None of the above

Explicación

Pregunta 23 de 40

1

Max Plank found his constant h

Selecciona una de las siguientes respuestas posibles:

  • To get same result as Rayleigh and Jeans

  • To describe experimental intensity distribution of blackbody at ultraviolet region

  • To describe Compton scattering

  • To describe experimental intensity distribution of blackbody at long wavelengths

  • To describe experimental intensity distribution of blackbody at all wavelengths

Explicación

Pregunta 24 de 40

1

Energy and momentum of photon is respectively:

Selecciona una de las siguientes respuestas posibles:

  • ħω; 1/λ

  • ħω; 2πħ/λ

  • m0c^2; 2π/λ

  • m0c^2; 2πħ/λ

  • ħω; m0c^2

Explicación

Pregunta 25 de 40

1

Nucleus of which element has no neutron:

Selecciona una de las siguientes respuestas posibles:

  • Deuterium

  • Tritium

  • All nucleus for all elements

  • Hydrogen

  • Helium

Explicación

Pregunta 26 de 40

1

The number of electron states in a shell with principal quantum number n = 3 is:

Selecciona una de las siguientes respuestas posibles:

  • 3

  • 15

  • 18

  • 19

  • 25

Explicación

Pregunta 27 de 40

1

The activity of radioactive substance is

Selecciona una de las siguientes respuestas posibles:

  • –dN/dt

  • dN/dt

  • N0

  • N

  • Ndt

Explicación

Pregunta 28 de 40

1

A hydrogen atom is in its ground state. Incident on the atom is a photon having an energy of 10.5 eV. What is the result?

Selecciona una de las siguientes respuestas posibles:

  • The atom is excited to a higher allowed state

  • The atom is ionized

  • The photon passes by the atom without interaction

Explicación

Pregunta 29 de 40

1

A hydrogen atom makes a transition from the n = 3 level to n = 2 level. It then makes a transition from the n = 2 level to the n = 1 level. Which transition results in emission of the longest-wavelength photon?

Selecciona una de las siguientes respuestas posibles:

  • The first transition

  • The second transition

  • Either transition because the wavelengths are the same for both

Explicación

Pregunta 30 de 40

1

A section of hollow pipe and a solid cylinder
have the same radius, mass, and length. They
both rotate about their long central axes with
the same angular speed. Which object has
the higher rotational kinetic energy?

Selecciona una de las siguientes respuestas posibles:

  • The hollow pipe

  • The solid cylinder

  • They have the same rotational kinetic energy

  • Impossible to determine

Explicación

Pregunta 31 de 40

1

Two spheres roll down an incline, starting
from rest. Sphere A has the same mass and
radius as sphere B, but sphere A is solid
while sphere B is hollow. Which arrives at
the bottom first?

Selecciona una de las siguientes respuestas posibles:

  • Sphere A

  • Sphere B

  • Both arrive

  • At the same time

  • Impossible to determine

Explicación

Pregunta 32 de 40

1

Two solid spheres roll down an incline,
starting from rest. Sphere A has twice the
mass and twice the radius of sphere B.
Which arrives at the bottom first?

Selecciona una de las siguientes respuestas posibles:

  • Sphere A

  • Sphere B

  • Both arrive at the same time

  • Impossible to determine

Explicación

Pregunta 33 de 40

1

Which of the following statements is not true regarding a mass- spring system that moves with simple harmonic motion in absence of friction?

Selecciona una de las siguientes respuestas posibles:

  • The total energy of the system remains constant

  • The energy of the system is continually transformed between kinetic and potential energy

  • The total energy of the system is proportional to the square of the amplitude

  • The potential energy stored in the system is greatest when the mass passes through the equilibrium position.

Explicación

Pregunta 34 de 40

1

For an object undergoing simple harmonic motion,

Selecciona una de las siguientes respuestas posibles:

  • The amplitudes are usually regarded as being large

  • The acceleration is greatest when the displacement is greatest

  • The acceleration is greatest when the speed is greatest

  • The maximum potential energy is larger than the maximum kinetic energy

  • The displacement is greatest when the speed is greatest

Explicación

Pregunta 35 de 40

1

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

Selecciona una de las siguientes respuestas posibles:

  • Conservation of momentum

  • Conservation of energy

  • Newton’s third law

  • Conservation of angular momentum

Explicación

Pregunta 36 de 40

1

The moment of inertia of a body depends on

Selecciona una de las siguientes respuestas posibles:

  • The angular velocity

  • The angular acceleration

  • The mass distribution

  • The torque acting on the body

Explicación

Pregunta 37 de 40

1

The moment of inertia of a wheel about its axle does not depend upon its:

Selecciona una de las siguientes respuestas posibles:

  • Diameter

  • Mass

  • Distribution of mass

  • Speed of rotation

Explicación

Pregunta 38 de 40

1

A mechanical wave generally does NOT

Selecciona una de las siguientes respuestas posibles:

  • Move the medium from one place to another

  • Move through a medium

  • Move through solids

  • Disturb the medium

Explicación

Pregunta 39 de 40

1

A woman sits on a spinning stool with her arms folded. When she extends her arms, which of the following occurs

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación

Pregunta 40 de 40

1

In elastic collision between the two bodies __________.

Selecciona una de las siguientes respuestas posibles:

  • 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

Explicación