An electron moves in a circular orbit of radius 10 cm with a constant speed of 4 . 0 × 10 6 ms − 1 . Determine the electric current at a point on the orbit.

Given that, Circular orbit of radius, r = 10 cm Speed of electron, v = 4.0 × 10 6 ms − 1 Expression for time period, T = 2 π r v ∴ v = 1 T = 4 × 10 6 2 π × 0.10 s − 1 I = v × e = 4 × 10 6 × 1.6 × 10 − 19 2 π × 0.10 = 1.02 × 10 − 12 A .

A metal wire of specific resistance 64 × 10 − 8 Ωm and length 1.98 m has a resistance of 7 Ω . Find its radius.

Given that, Specific resistance of the wire is 64 × 10 − 8 Ω m length of the wire is 1.98 m resistance of the metal wire is 7 Ω Expression for resistance of a metal wire is, R = ρ l A Let’s assume radius of the copper wire is r As R = ρ l A = ρ l π r 2 ∴ r 2 = ρ l π R = 64 × 10 − 8 × 1.98 × 7 22 × 7 = 5.76 × 10 − 8 m 2 or r = 2.4 × 10 − 4 m

Calculate the resistance of a 2 m long nichrome wire of radius 0 . 321 mm . Resistivity of nichrome is 15 × 10 − 6 Ωm . If a potential difference of 10 V is applied across this wire, what will be the current in the wire?

Given that, Resistivity of nichrome is 15 × 10 − 6 Ωm Length of the nichrome wire is, l = 2 m Radius of the nichrome wire is, r = 0.321 mm Expression for resistance of the nichrome wire is R = ρ l A = ρ l π r 2 R = 15 × 10 − 6 × 2 π × 0.321 2 = 9.26 Ω According to Ohm’s law, relation between current and voltage is V = I × R Amount of current is I = V R I = 10 9.26 A = 1.08 A

EASY

12th CBSE

IMPORTANT

Earn 100

In a hydrogen atom, the electron makes about $0.6 \times 10^{16}$ revolutions per second around the nucleus. Determine the average current at any point on the orbit of the electron.

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 6

An electron moves in a circular orbit of radius

10 cm

with a constant speed of

4.0 \times 10^{6} {ms}^{- 1}

. Determine the electric current at a point on the orbit.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 7

In a hydrogen discharge tube, the number of protons drifting across a cross-section per second is

1.1 \times 10^{18}

, while the number of electrons drifting in the opposite direction across another cross-section is

3.1 \times 10^{18}

per second. Find the current flowing in the tube.

EASY

12th CBSE

IMPORTANT

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

A voltage of

30 V

is applied across a color-coded carbon resistor with first, second and third rings of blue, black and yellow colors. What is the current flowing through the resistor?

EASY

12th CBSE

IMPORTANT

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

A potential difference of

10 V

is applied across a conductor of resistance

1 k Ω

. Find the number of electrons flowing through the conductor in

5

minutes.

EASY

12th CBSE

IMPORTANT

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

What length of a copper wire of cross-sectional area

0.01 {mm}^{2}

would be required to obtain a resistance of

1 k Ω

? The resistivity of copper

= 1.7 \times 10^{- 8} Ωm

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 4

A metal wire of specific resistance

64 \times 10^{- 8} Ωm

and length

1.98 m

has a resistance of

7 Ω

. Find its radius.

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 5

Calculate the resistance of a

2 m

long nichrome wire of radius

0.321 mm

. Resistivity of nichrome is

15 \times 10^{- 6} Ωm

. If a potential difference of

10 V

is applied across this wire, what will be the current in the wire?

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 3 - Current Electricity>Problems For Practice>Q 6

An electron beam has an aperture of

1.0 {mm}^{2}

. A total of

6 \times 10^{16}

electrons flow through any perpendicular cross-section per second. Calculate (i) the current and (ii) the current density in the electron beam.

In a hydrogen atom, the electron makes about 0.6×1016 revolutions per second around the nucleus. Determine the average current at any point on the orbit of the electron.

Important Questions on Current Electricity

Learn and Prepare for any exam you want !

In a hydrogen atom, the electron makes about $0.6 \times 10^{16}$ revolutions per second around the nucleus. Determine the average current at any point on the orbit of the electron.