EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th April 2019 Shift 2>Q 75

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IMPORTANT

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In a conductor, if the number of conduction electrons per unit volume is $8.5 \times 10^{28} m^{- 3}$ and mean free time is $25 f s$ (femtosecond), its approximate resistivity is: $(m_{e} = 9.1 \times 10^{- 31} k g)$

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Important Questions on Current Electricity

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 1>Q 76

When the switch

S,

in the circuit shown, is closed, then the value of current

i

will be:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 1>Q 77

Drift speed of electrons, when

1.5 A

current flows in a copper wire of cross section

5 {mm}^{2}

is

v_{d} .

If the electron density in copper is

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

the value of

v_{d}

in

mm s^{- 1}

is close to (Take charge of an electron to be

= 1.6 \times 10^{- 19} C

)

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 1>Q 78

A resistance is shown in the figure. Its value and tolerance are given respectively by:
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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 1>Q 79

A copper wire is stretched to make it

0.5 %

longer. The percentage change in its electrical resistance if its volume remains unchanged is:

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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 2>Q 80

A carbon resistance has the following colour code. What is the value of the resistance?
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IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 9th January 2019 Shift 2>Q 81

In the given circuit the internal resistance of the

18 V

cell is negligible. If

R_{1} = 400 Ω, R_{3} = 100 Ω

and

R_{4} = 500 Ω

and the reading of an ideal voltmeter across

R_{4}

is

5 V,

then the value of

R_{2}

will be:

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 8th April 2019 Shift 1>Q 82

For the circuit shown, with

R_{1} = 1.0 Ω

,

R_{2} = 2.0 Ω

,

E_{1} = 2 V

and

E_{2} = E_{3} = 4 V,

the potential difference between the points

‘ a ’

and

‘ b ’

is approximately (

i n V

):

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JEE Main

IMPORTANT

EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR PHYSICS>Chapter 14 - Current Electricity>JEE Main - 8th April 2019 Shift 1>Q 83

A

200 Ω

resistor has certain colour code. If one replaced the red colour by green in the code, the new resistance will be: