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JEE Main

IMPORTANT

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In the circuit shown, the resistance r is a variable resistance. If for $r = f R$ , the heat generation in r is maximum then the value of $f$ is

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Important Questions on Current Electricity

MEDIUM

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th April 2016>Q 120

To know the resistance

G

of a galvanometer by half deflection method, a battery of emf

V_{E}

and resistance

R

is used to deflect the galvanometer by angle

θ

. If a shunt of resistance

S

is needed to get half deflection the

G

R

and

S

are related by the equation:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 3rd April 2016>Q 121

The temperature dependence of resistance of

Cu

and undoped

Si

in the temperature range

300 - 400 K

is best described by

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JEE Main

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 3rd April 2016>Q 122

A galvanometer having a coil resistance of

100 Ω

gives a full scale deflection, when a current of

1 mA

is passed through it. The value of the resistance, which can convert this galvanometer into ammeter giving a full scale deflection for a current of

10 A

, is:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 10th April 2016>Q 123

The resistance of an electrical toaster has a temperature dependence given by

R (T) = R_{0} [1 + α (T - T_{0})]

in its range of operation. At

T_{0} = 300 K, R = 100 Ω and a t T = 500 K, R = 120 Ω

. The toaster is connected to a voltage source at

200 V

and its temperature is raised at a constant rate from

300 to 500 K

30 s

. The total work done in raising the temperature is :

Note: This question was awarded as the bonus since all options were incorrect in the exam.

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 10th April 2015>Q 124

10 V

battery with internal resistance

1 Ω

and a

15 V

battery with internal resistance

0.6 Ω

are connected in parallel to a voltmeter (see figure). The reading in the voltmeter will be close to:

Question Image

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 10th April 2015>Q 125

Suppose the drift velocity

v_{d}

in a material varied with the applied electric field E as

v_{d} \propto \sqrt{E}

. Then

V - I

graph for a wire made of such a material is best given by:

MEDIUM

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 4th April 2015>Q 126

In the circuit shown, the current in the

1 Ω

resistor is:

HARD

JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 4th April 2015>Q 127

When

5 V

potential difference is applied across a wire of length

0.1 m

, the drift speed of electrons is

2.5 \times 10^{- 4} m s^{- 1}

. If the electron density in the wire is

8 \times 10^{28} m^{- 3}

, the resistivity of the material is close to:

In the circuit shown, the resistance r is a variable resistance. If for r=fR , the heat generation in r is maximum then the value of f is

Important Questions on Current Electricity

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In the circuit shown, the resistance r is a variable resistance. If for $r = f R$ , the heat generation in r is maximum then the value of $f$ is