HARD

12th West Bengal Board

IMPORTANT

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Two conductors have the same resistance at $0 ° C$ But their temperature coefficient of resistance are $α_{1}$ and $α_{2}$ . The respective temperature coefficient of their series and parallel combination are nearly.

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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 6

A battery of emf

E

Has as internal resistance

r .

A variable resistance

R

Is connected to the terminals of the battery. A current

i

Is drawn from the battery.

V

Is the terminal potential difference. If

R

Alone is gradually reduced to zero, which of the following best describes

i

and

V .

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 7

The density of copper is

9 \times 10^{3} k g / m^{3}

and its atomic weight is

63.5 u .

Each copper atom provides one free electron. Estimate the number of free electrons per cubic metre in copper

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 8

The amount of charge

Q

passed in time

t

through a cross section of a wire is

Q = 5 t^{2} + 3 t + 1 .

The value of current at time

t = 5 s

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 9

Resistance of a wire at

20 ° C

20 Ω

and

500 ° C

60 Ω

At what temperature its resistance is

25 Ω .

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 10

Two different conductors have same resistance at

0 ° C .

It is found that the resistance of the first conductor at

t_{2} °

C

is equal to the resistance of the second conductor at

t_{2} ° C .

The ratio of temperature co-efficients of resistance of the conductors,

\frac{α}{α_{2}}

MEDIUM

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 11

A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it

MEDIUM

12th West Bengal Board

IMPORTANT

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

If a rod has resistance

4 Ω

and if rod is turned as half circle, then the resistance along diameter is

HARD

12th West Bengal Board

IMPORTANT

A Text Book of PHYSICS PART 2 : CLASS 12>Chapter 5 - Current Electricity>EXERCISE 5>Q 13

A

material

B

has twice the specific resistance of

A .

A

circular wire made of

B

has twice the diameter of a wire made of

A .

Then for the two wires to have the same resistance, the ratio

\frac{ι_{B}}{ι_{A}}

of their respective lengths must be

Two conductors have the same resistance at 0°C But their temperature coefficient of resistance are α1 and α2. The respective temperature coefficient of their series and parallel combination are nearly.

Important Questions on Current Electricity

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Two conductors have the same resistance at $0 ° C$ But their temperature coefficient of resistance are $α_{1}$ and $α_{2}$ . The respective temperature coefficient of their series and parallel combination are nearly.