A 10 C of charge flows through a wire in 5 minutes. The radius of the wire is 1 mm . It contains 5 × 10 22 electrons per centimetre 3 . Calculate the current and drift velocity.

Given that, Charge flow through a wire is 10 C and the radius of the wire is 1 mm Number of electrons per cm 3 , n = 5 × 10 22 Expression of current is I = q t Or I = 10 C 5 × 60 s = 3.33 × 10 − 2 A Expression for drift velocity is v d = I e n A = I e n π r 2 v d = 3.33 × 10 − 2 16 × 10 − 19 × 5 × 10 2 2 × 10 6 × 314 × 10 − 3 2 v d = 1.326 × 10 − 6 m s − 1

A 10 C of charge flows through a wire in 5 minutes. The radius of the wire is 1 mm . It contains 5 × 10 22 electrons per centimetre 3 . Calculate the current and drift velocity.

Given that, Charge flow through a wire is 10 C and the radius of the wire is 1 mm Number of electrons per cm 3 , n = 5 × 10 22 Expression of current is I = q t Or I = 10 C 5 × 60 s = 3.33 × 10 − 2 A Expression for drift velocity is v d = I e n A = I e n π r 2 v d = 3.33 × 10 − 2 16 × 10 − 19 × 5 × 10 2 2 × 10 6 × 314 × 10 − 3 2 v d = 1.326 × 10 − 6 m s − 1

EASY

12th CBSE

IMPORTANT

Earn 100

A $10 C$ of charge flows through a wire in $5$ minutes. The radius of the wire is $1 mm$ . It contains $5 \times 10^{22}$ electrons per ${centimetre}^{3}$ . Calculate the current and drift velocity.

Important Questions on Current Electricity

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 8

A copper wire of diameter

0.16 cm

is connected in series to an aluminium wire of diameter

0.25 cm

. A current of

10 A

is passed through them. Find current density in the copper wire. The number of free electrons per unit volume of aluminium wire is

10^{29} m^{- 3}

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 8

A copper wire of diameter

0.16 cm

is connected in series to an aluminium wire of diameter

0.25 cm

. A current of

10 A

is passed through them. Find drift velocity of free electrons in the aluminium wire. The number of free electrons per unit volume of aluminium wire is

10^{29} m^{- 3}

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 9

A current of

30

ampere is flowing through a wire of cross‐sectional area

2 {mm}^{2}

. Calculate the drift velocity of electrons. Assuming the temperature of the wire to be

27 ° C

, also calculate the

r m s

velocity at this temperature. Which velocity is larger? Given that Boltzmann’s constant

= 1.38 \times 10^{- 23} {JK}^{- 1}

, density of copper

8.9 g {cm}^{- 3}

, atomic mass of copper

= 63

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 10

What is the drift velocity of electrons in the silver wire of length

1 m

, having cross-sectional area

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

and carrying a current of

10 A

? Given atomic mass

= 108

, density of silver

10.5 \times 10^{3} kg m^{- 3}

, charge on electron

= 1.6 \times 10^{- 19} C

and Avogadro’s number

= 6.023 \times 10^{26}

per kg-atom.

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 11

When a potential difference of

1.5 V

is applied across a wire of length

0.2 m

and area of cross-section

0.3 {mm}^{2}

, a current of

2.4 A

flows through the wire. If the number density of free electrons in the wire is

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

, calculate the average relaxation time. Given that mass of electron

= 9.1 \times 10^{- 31} kg

and charge on electron

= 1.6 \times 10^{- 19} C

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 1

A potential difference of

4.5 V

is applied across a conductor of length

0.1 m

. If the drift velocity of electrons is

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

, find the electron mobility.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 2

The number density of electrons in copper is

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

A current of

1 A

flows through a copper wire of length

0.24 m

and area of cross-section

1.2 {mm}^{2}

, when connected to a battery of

3 V

. Find the electron mobility.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 3

Mobilities of electrons and holes in a sample of intrinsic germanium at room temperature are

0.54 m^{2} V^{- 1} s^{- 1}

and

0.18 m^{- 1} V^{- 1} s^{- 1}

respectively. If the electron and hole densities are equal to

3.6 \times 10^{19} m^{- 3}

calculate the germanium conductivity.

A 10 C of charge flows through a wire in 5 minutes. The radius of the wire is 1 mm. It contains 5×1022 electrons per centimetre3. Calculate the current and drift velocity.

Important Questions on Current Electricity

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A $10 C$ of charge flows through a wire in $5$ minutes. The radius of the wire is $1 mm$ . It contains $5 \times 10^{22}$ electrons per ${centimetre}^{3}$ . Calculate the current and drift velocity.