A car has a fresh storage battery of emf 12 V and internal resistance 5 . 0 × 10 - 2 Ω . The starter motor draws a current of 90 A . Find the terminal voltage of the battery when the starter is on.

Given, ε = 12 V r = 5 . 0 × 10 - 2 Ω I = 90 A The relationship between the terminal voltage and emf is given by V = ε − I r V = 12 − ( 90 × 5 × 10 - 2 ) V = 12 - ( 450 × 10 - 2 ) V = 12 - 4 . 5 V = 7 . 5 V Therefore, terminal voltage of the battery is 7 . 5 V

MEDIUM

12th West Bengal Board

IMPORTANT

Earn 100

Two batteries of emf $12 V$ and $6 V$ and internal resistance $0.2 Ω$ and $0.1 Ω$ respectively are connected in opposition through a resistor $3.7 Ω$ . Calculate the terminal voltage of the two batteries.

Important Questions on Current Electricity

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 23

P, Q, R, S

resistances from the four arms of a Wheatstone bridge whose values are

2 Ω, 2 Ω, 2 Ω

and

3 Ω

respectively. What would be the resistance that should be connected in parallel with $S$ so that the null condition is obtained for the P.O. Box.

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 24

A car has a fresh storage battery of emf

12 V

and internal resistance

5.0 \times 10^{- 2} Ω

. The starter motor draws a current of

90 A

. Find the terminal voltage of the battery when the starter is on.

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 24

After long use, the internal resistance of the battery increases to

500 Ω

. What maximum current can be drawn from the battery ? Assume the e.m.f. of the battery to remain unchanged.

EASY

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 24

If the discharged battery is charged by an external emf source, is the terminal voltage of the battery during charging greater or less than

12 V

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 25

A variable rheostat of $2 KΩ$ , Fig. is used to control the p.d. across a $500 Ω$ load $R_{L}$ . If the resistance $A B$ is $500 Ω$ , what is p.d. across $R_{L} ?$ If $R_{L}$ is removed, what should be the resistance $B C$ to get $40 V$ between $B$ and $C$ .

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 26

A heating element using nichrome connected to a

230 V

supply draws an initial current of

3.2 A

which settles after a few second to a steady value of

2.8 A

. Find the steady temperature of the heating element. If the room temperature is

27 ° C

. The temperature co-efficient of resistance of nichrome averaged over the temperature range involved in

1.70 \times 10^{- 4} C^{- 1}

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 27

Calculate the conductance and conductivity of the material of a wire of resistance

0.01 Ω

, area of cross-section

10^{- 4} m^{2}

and length

0.1 m

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 27

Calculate the resistivity of the material of a wire

1.0 m

long,

0.4 mm

in diameter and having a resistance of

2.0 ohm

Two batteries of emf 12 V and 6 V and internal resistance 0.2 Ω and 0.1 Ω respectively are connected in opposition through a resistor 3.7 Ω. Calculate the terminal voltage of the two batteries.

Important Questions on Current Electricity

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Two batteries of emf $12 V$ and $6 V$ and internal resistance $0.2 Ω$ and $0.1 Ω$ respectively are connected in opposition through a resistor $3.7 Ω$ . Calculate the terminal voltage of the two batteries.