Objective Type Question and Answers On Class 12 Physics Chapter 3 Current Electricity

1 A galvanometer acting as a volt meter will have with its coil.

A a high resistance in parallel

B a high resistance in series

C a low resistance in parallel

D a low resistance in series

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Answer:a high resistance in series

2 The length and radius of an electric resistance of a certain wire are doubled simultaneously, then the:

A resistance will be doubled and specific resistance will be halved

B resistance will be halved and specific resistance will remain uncharged

C resistance will be halved and the specific resistance will be doubled

D resistance and specific resistance will both remain uncharged

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Answer:resistance will be halved and specific resistance will remain uncharged

3 Ohm’s law is valid when the temperature of conductor is :

A very low

B very high

C varying

D constant

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Answer:constant

4 n resistances, each of R Ω, are connected in parallel gives an equivalent resistance of R Ω. If these resistances were , connected in series, the combination would have a resistance in Ω is equal to

A n²R

B R/n²

C R/n

D nR

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Answer:n²R

5 Emf is measured in :

A joule

B joule/coulomb

C joule-coulombs

D joule/coulomb/metre

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Answer:joule/coulomb

6 A potential difference of 10 V is applied across a conductance of 2 S. The current in the conductor will be :

A 20 A

B 5 A

C 0.2 A

D None of these

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Answer:20 A

7 The temperature coefficient of resistance is expressed in :

A °C

B °C^-1

C m°C^-1

D None of these

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Answer:°C-1

8 1 kilowatt hour is commonly known as :

A unit

B 1 faraday

C 1 curie

D None of these

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Answer:unit

9 In an experiment with potentiometer, null point with a cell is found at 240 cm. When the cell is shunted with a resistance 2 Ω, the null point becomes 120 cm internal resistance of cell is :

A 4 Ω

B 2 Ω

C 1 Ω

D 1/2 Ω

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Answer:2/Ω

10 The phenomenon of super-conductivity was discovered by :

A Ohm

B Onnes

C Edison

D None of these

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Answer:Onnes

11 Copper wire is used as connecting wire because :

A copper has high electrical resistivity

B copper has low electrical resistivity

C copper has low electrical conductivity

D copper has high value of elasticity

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Answer:copper has low electrical resistivity

12 A wire of resistance 3 Ω is cut into three pieces, which are then joined to form a triangle. The equivalent resistance between any corners of the triangle is :

A 2/3 Ω

B 3/2 Ω

C 1/2 Ω

D 1/3 Ω

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Answer:2/3 Ω

13 The example of a non-ohmic resistance is:

A copper wire

B fi lament lamp

C carbon resistor

D diode

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Answer:diode

14 How many different resistances are possible with two equal resistors?

A 2

B 3

C 4

D 5

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Answer:3

15 The speed at which tjie current travels in a conductor is nearly:

A 3 × 10⁴ ms^-1

B 3 × 10⁶ ms^-1

C 3 × 10⁸ ms^-1

D 3 × 10¹⁰ ms^-1

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Answer:3 × 10⁴ ms^-1

16 The heat sensitive device whose resistivity changes very rapidly with change of temperature is called a :

A resistor

B super-conductor

C thermocouple

D thermistor

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Answer:thermistor

17 In following figure shows currents in a part of electrical circuit, then the value of/(in ampere) is given by :

Class 12 Physics Chapter 3 Current Electricity

A 0.3 A

B 0.5 A

C 1.3 A

D None of these

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Answer:0.3 A

18 An electric heating element consumes 500 W, when connected to a 100 V line. If the line voltage becomes 150 V, the power consumed Will be:

A 500 W

B 750 W

C 1000 W

D 1125 W

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Answer:750 W

19 A uniform w ire connected across a supply produces heat H per second. If wire is cut into three equal parts and all the parts are connected in parallel across the same supply, the heat produced per second will be :

A H/9

B 9 H

C 3 H

D H/3

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