Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 8

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A cell of $emf E$ having an internal resistance $r$ is connected to external resistance $R$ . The potential difference $V$ across the resistance $R$ varies with $R$ as shown by the curve:

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Important Questions on Current Electricity

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 9

n

identical light bulbs, each designed to draw power

P

from a certain voltage supply are joined in series and that combination is connected across that supply. The power consumed by one bulb will be-

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 10

To get maximum current through a resistance of

2.5 Ω

, one can use

m

rows of cells, each row having

n

cells. The internal resistance of each cell is

0.5 Ω

. What are the values of

n & m

, if the total number of cells is

45

?

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 11

50 V

battery is supplying a current of

10 amp

when connected to a resistor. If the efficiency of battery at this current is

25 %

. Then internal resistance of the battery is:

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 12

A battery is supplying power to a tape-recorder by cable of resistance of

0.02 Ω

. If the battery is generating

50 W

power at

5 V

, then power received by tape-recorder is : (neglect internal resistance of battery)

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 13

In the shown circuit the resistance $R$ can be varied
Question Image
The variation of current through $R$ against $R$ is correctly plotted as:

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 14

Specific resistance of a wire depends on its

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 15

The electric current passes through a metallic wire produces heat because of

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Practice Book for KVPY Aptitude Test - Stream SX Physics>Chapter 3 - Current Electricity>Exercise#1>Q 16

For a metallic wire, the ratio

\frac{V}{i}

(

V

is applied potential difference and

i

is current flowing) is