NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 7

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12th ICSE

IMPORTANT

Earn 100

Show that effective resistance in series combination increases. While that in parallel combination decreases. Two wires of iron and copper of same dimensions are connected in series. The iron wire burns out but the copper wire not even visible glow.Explain.

Important Questions on Electric Resistance and Ohm's Law

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12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 1

A current of

20 μA

flows in a wire for

30

seconds. Find the amount of charge and the number of free electrons transferred through the wire.

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12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 2

A current of $1 A$ is flowing through a conductor. How many electrons pass through any cross-section of the conductor per second ?

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12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 2

A current of

1 A

is flowing through a conductor. How many electrons pass through any cross-section of the conductor in

1.6

second?

EASY

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IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 3

The cross-sectional area of a wire is

1.0 \times 10^{- 7} m^{2}

and the density of free electrons is

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

. What will be the drift velocity of the free electrons for a current of

3.2 A

in the wire?

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12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 4

90 C

charge flows for

75

minutes in silver wire of diameter

1.0 mm

. The free-electron density in the wire is

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

. Find the current and the drift velocity of free electrons in the wire.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 5

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area

1.0 \times 10^{- 7} m^{2}

carrying a current of

1.5 A

. Assume that each copper atom contributes one conduction electron. The density of copper is

9.0 \times 10^{- 3}

kg

m^{- 3}

and its atomic mass is

63.5

. Take Avogadro's number

N = 6.0 \times 10^{23} {mol}^{- 1}

.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 6

Calculate the electric current density in a uniform wire connected to a battery of emf

3.5 V

and negligible internal resistance. The resistance of the wire is

2.0 Ω

and its area of cross-section is

0.70 \times 10^{- 6} m^{2}

.

HARD

12th ICSE

IMPORTANT

NOOTAN ISC PHYSICS Class 12 Part-1>Chapter 5 - Electric Resistance and Ohm's Law>QUESTIONS>Q 7

A

3.0 m

long copper wire is carrying a current of

3.0 A

. How long does it take for an electron to drift from one end of the wire to the other? The cross-sectional area of the wire is

2.0 \times 10^{- 6} m^{- 2}

and the number of conduction electrons in copper is

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

.