Question 1
Question
What are the minimum requirements to cause the flow of current?
Answer
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A voltage source, an ammeter, a conductor and an insulator
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A voltage source, a switch and a resistor
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A voltage source and a conductor
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A voltage source, a conductor and an insulator
Question 2
Question
Out of the following, select the best conductor of electricity.
Answer
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Graphite
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China Clay
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Porcelain
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None of these
Question 3
Question
Which of the following statements is correct?
Answer
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The resistance does not play an important role in electrical engineering.
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The resistance of a wire does not depend upon its material.
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The resistance of most of the materials is independent of the temperature.
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The resistance of conductor is the hindrance by which the conductor opposes the flow of the current.
Question 4
Question
Resistance of a conductor increases when
Question 5
Question
The specific resistance ρ depends upon
Answer
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The area of cross-section and the length of the conductor
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The material of the conductor, its area of cress-section and length
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The nature of the material of the conductor only
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The area of cross-section of the conductor
Question 6
Question
The specific resistance ρ is defined as
Answer
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resistance of a conductor which has a length of 1 m and cross-section of 1 m2 at 20C
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resistance of any conductor at 25C
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resistance of any conductor at 20C
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resistance of a conductor which has a length of 1 m and cross-section of 1 cm2 at 20C
Question 7
Question
The resistance of a conductor, when its temperature is increased
Answer
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remains constant
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increases
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varies
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decreases
Question 8
Question
It was experimentally found by James Prescott Joule that the heat produced in a current carrying conductor is proportional to
Question 9
Question
The value of Joule's mechanical equivalent of heat, J, is equal to
Answer
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4.2 calories per Joule
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2.4 Joules per calorie
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4.2 Joules per calorie
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4.2 Joules
Question 10
Question
Temperature coefficient of a conductor is defined as the
Answer
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increase in resistance per ohm per degree centigrade
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increase in resistance per degree centigrade
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increase in resistance per degree absolute
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decrease in resistance per ohm per degree centigrade
Question 11
Question
When current flows in a conductor, heat is produced because
Answer
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heat α I²
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of electronic collision
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of interatomic collision
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of Joule's law
Question 12
Question
Heating effect of current has undesirable side effect in
Answer
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electric oven
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electric iron
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immersion heater
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vacuum cleaner
Question 13
Question
The resistance of carbon (filament in carbon-filament lamps) when its temperature is decreased
Answer
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increases
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decreases
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remains the same
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increases enormously
Question 14
Question
The curve representing Ohm's law is
Answer
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a parabola
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linear
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sine function
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a hyperbola
Question 15
Question
The condition in Ohm's law is that
Answer
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ratio V/I should be constant
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current should be proportional to voltage
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the temperature should remain constant
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the temperature should vary
Question 16
Question
Ohm's law does not apply to
Question 17
Question
Ohm's law is applicable to
Answer
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electric arc
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rectifying devices
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gas discharge lamps
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none of these
Question 18
Question
Ohm's law can be applied with certain reservations to
Answer
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rectifying devices
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semiconductors
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electrolytes
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thermionic valves
Question 19
Question
The presence of an electric current is made known by
Answer
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flashing
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effects produced
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cracking
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electric shock
Question 20
Question
An electric current can neither be ____ nor ____.
Question 21
Question
The presence of the current is only made known by the effect it produces. Three important effects are
Answer
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heating, electric shock and generation
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generation, chemical and electric shock
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heating, magnetic and electric shock
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heating, magnetic and chemical
Question 22
Question
Voltage applied across a circuit, acts as
Answer
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mass of electrons
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negative ions
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a component of current
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a force
Question 23
Question
In a series circuit the current is
Question 24
Question
In a parallel circuit the potential difference across the resistance
Question 25
Question
The resistance R1 and R2 are connected in parallel. The ratio of values of resistance R1 : R2 is 4 : 1. The currents in R1 : R2 will be equal to
Question 26
Question
A resistance of 4 ohms is connected across 100 V supply. When another resistor 'R' ohms is connected in parallel with 4 ohms, the total current taken from supply was found to be 50 A. The value of resistance 'R' is
Answer
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2 ohms
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3 ohms
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5 ohms
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4 ohms
Question 27
Question
The voltage applied across an electric press was reduced by 50%. The power consumed by the press will be reduced by
Question 28
Question
Two electric presses are connected in parallel. The resistance of the first press is 100 ohms and that of the second is 300 ohms. The total current taken by both the presses is 4 A. The ratio of current taken by first : second will be equal to
Answer
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2 : 3
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1 : 3
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3 : 1
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1.2 : 3
Question 29
Question
Three elements having conductance G1. G2 and G3 are connected in parallel. Their combined conductance will be
Question 30
Question
Four resistance R1, R2, R3 and R4 are connected in series against 220 V supply. The resistances are such that R1 > R2 > R3 > R4. The least power consumption will be in
Answer
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resistor R1
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resistor R4
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resistor R3
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resistor R2
Question 31
Question
When current flows through heater coil it glows but supply wiring does not glow because
Answer
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supply wiring is covered with insulation layer
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current through supply line flows at slower speed
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supply wires are made of superior material
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resistance of heater coil is more than that of supply wires
Question 32
Question
Resistors commonly used in power circuits are
Question 33
Question
International ohm is defined in terms of resistance of
Question 34
Question
Which of the following has negative coefficient of resistance?
Answer
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wire wound resistor
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non-metals
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thermistor
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metals
Question 35
Question
The current carrying capability of the fuse material depends on
Answer
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length
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material
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cross-sectional area
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all of these