Class 12 Moving Charges And Magnetism CBSE Questions & Answers

Class 12 · Moving Charges And Magnetism

This is Physics Class 12 Moving Charges and Magnetism CBSE Questions & Answers. There are 15 questions in this test with each question having around four answer choices.

Questions & Answers

The magnetic field at the center of a solenoid coil having n turns and carrying a current I in air is

A
\(\mu_0 n I^2\)
B
\(\mu_0 n^2 I\)
C
\(\mu_0 n I\)
Correct
D
\(2\pi\mu_0 n I\)

The magnetic field at the center of a toroidal coil having n turns,radius r and carrying a current I in air is

A
\(\frac{\mu_0 N I}{2\pi r}\)
Correct
B
\(\frac{\mu_0 N I}{\pi r}\)
C
\(\frac{\mu_0 N^2 I}{2\pi r}\)
D
\(\frac{\mu_0 N I^2}{2\pi r}\)

For two parallel wires carrying currents Ia and Ib seperated by a distance d, the magnitude of force acting on length L of any of the wires is

A
\(\frac{\mu_0 L I_a^2 I_b^2}{2\pi d}\)
B
\(\frac{\mu_0 L I_a I_b}{2\pi d^2}\)
C
\(\frac{\mu_0 L^2 I_a I_b}{2\pi d}\)
D
\(\frac{\mu_0 L I_a I_b}{2\pi d}\)
Correct

A rectangular current-carrying coil having n turns,area A and a current I flowing, in a uniform magnetic field B experiences a maximum ,torque equal to

A
nIB
B
nIA
C
nIAB
Correct
D
IAB

magnetic moment of a single-turn current loop of aluminium wire of area A,carrying a current I in a wire of diameter d is

A
IA
Correct
B
μIA
C
IA/d
D
IAd

For a single turn circular coil of dipole moment m the magnetic field on the axis x >> R (distance x and coil radius R) the magnitude of magnetic field is

A
\(\frac{\mu_0 m^2}{2\pi x^3}\)
B
\(\frac{\mu_0 m}{2\pi x}\)
C
\(\frac{\mu_0 m}{2\pi x^2}\)
D
\(\frac{\mu_0 m}{2\pi x^3}\)
Correct

magnitude of the magnetic moment of an electron of mass me if e is the charge on the electron and angular momentum is l, is

A
\(\frac{e}{2m_e}l^2\)
B
\(\frac{e}{2m_e}l\)
Correct
C
\(\frac{e^2}{2m_e}l\)
D
\(\frac{e}{4m_e}l\)

In a moving coil galvanometer the current through the coil produces a torque to turn the coil. The torque is balanced by

A
gravitational torque
B
eddy current torque
C
magnetic moment
D
a helical spring deflection
Correct

For measuring μA current the galvanometer is

A
connected in parallel series
B
always connected in series
Correct
C
connected in series parallel
D
always connected in parallel

Shunt resistance is added to the galvanometer

A
In series to the galvanometer to lower the input resistance of the meter
B
In parallel to the galvanometer to lower the input resistance of the meter
Correct
C
In parallel to the galvanometer to maintain the input resistance of the meter
D
In parallel to the galvanometer to raise the input resistance of the meter

A Current carrying wire produces in its neighbourhood

A
zero field
B
magnetic field only
C
electric field only
D
electric and magnetic fields
Correct

The magnetic induction in air at point 1 cm away from a long wire that carries a current of 1 A, will be

A
\({\rm{3 }} \times {\rm{ 1}}0 - {\rm{5}}{\rm{T}}\)
B
\({\rm{2 }} \times {\rm{ 1}}0 - {\rm{5}}{\rm{T}}\)
Correct
C
\({\rm{4 }} \times {\rm{ 1}}0 - {\rm{5}}{\rm{T}}\)
D
\({\rm{1 }} \times {\rm{ 1}}0 - {\rm{5}}{\rm{T}}\)

A long straight wire carries an electric current of 2 A. The magnetic induction at a perpendicular distance of 5 m from the wire is (\(\mu = {\rm{4}}\pi {\rm{x1}}0 - {\rm{7Hm}} - {\rm{1}}\))

A
\({\rm{12 }} \times {\rm{1}}0 - {\rm{8}}{\rm{T}}\)
B
\({\rm{8 }} \times {\rm{ 1}}0 - {\rm{8}}{\rm{T}}\)
Correct
C
\({\rm{4 }} \times {\rm{ 1}}0 - {\rm{8}}{\rm{T}}\)
D
\({\rm{16 }} \times {\rm{ 1}}0 - {\rm{8}}{\rm{T}}\)

The magnetic field due to very long wire carrying current varies according to

A
square of the distance from the wire
B
inverse of the distance from the wire
Correct
C
linearly as the distance from wire
D
square root of the distance from wire

What should be the current in a circular coil of radius 5 cm to annul \({\rm{BH}} = {\rm{ 5 }} \times {\rm{ 1}}0 - {\rm{5}}\) T at the center?

A
4 A
Correct
B
40 A
C
1 A
D
0.4 A