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A magnet of magnetic moment $M$ is situated with its axis along the direction of a magnetic field of strength $B .$ The work done in rotating it by an angle of $180 °$ will be :-

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Important Questions on Magnetic Effect of Current

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A coil in the shape of an equilateral triangle of side

l

is suspended between the pole pieces of a permanent magnet such that

B

is in plane of the coil. If due to a current

i

in the triangle, a torque

τ

rests on it, the side

l

of the triangle is

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A magnet of total magnetic moment

10^{- 2} \hat{i} A m^{2}

is placed in a time varying magnetic field,

B \hat{i} (\cos ω t)

where

B = 1

Tesla and

ω = 0.125 rad s^{- 1}

. The work done for reversing the direction of the magnetic moment at

t = 1

second, is:

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A circular coil has moment of inertia

0.8 kg m^{2}

around any diameter and is carrying current to produce a magnetic moment of

20 A m^{2}

. The coil is kept initially in a vertical position and it can rotate freely around a horizontal diameter. When a uniform magnetic field of

4 T

is applied along the vertical, it starts rotating around its horizontal diameter. The angular speed the coil acquires after rotating by

60^{o}

will be :

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A bar magnet is held perpendicular to uniform magnetic field. The torque acting on the magnet is to be made half by rotating it. It should be rotated through an angle

(\sin 30 ° = 0.5, \sin 90 ° = 1)

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A magnetic dipole in a uniform magnetic field has: (Take zero potential energy when magnetic dipole is perpendicular to magnetic field)

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A magnetic dipole of moment

\vec{m}

is placed in the magnetic field

\vec{B}

. It is free to rotate about an axis about which its moment of inertia is

I

. It is displaced by a small angle

θ_{0} (θ_{0} < < 1)

at time

t = 0 s

and released. The dipole undergoes simple harmonic motion with angular frequency

ω

. Its potential energy at time

t

is : (Assume

\sin (α) \approx α, \cos (α) \approx 1 - \frac{α^{2}}{2}

α < < 1

)

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A coil of $50$ turns carrying a current of $2 A$ in a magnetic field of $0.5 T$ . The torque acting on the coil is

Question Image

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A $100$ turns coil shown in figure carries a current of $2 A$ in a magnetic field $B = 0.2 Wb m^{- 2} .$ The torque acting on the coil is

Question Image

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A magnetic dipole is acted upon by two magnetic fields which are inclined to each other at an angle of

75^{o}

. One of the fields has a magnitude of

15 mT

. The dipole attains stable equilibrium at an angle of

30^{o}

with this field. The magnitude of the other field (in

mT

) is close to

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A magnetic needle has a magnetic moment of

5 \times 10^{- 2} {Am}^{2}

and moment of inertia

8 \times 10^{- 6} {kgm}^{2}

. It has a period of oscillation of

2 s

in a magnetic field

\vec{B}

. The magnitude of magnetic field is approximately;

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

In a uniform magnetic field, the magnetic needle has a magnetic moment

9.85 \times 10^{- 2} A m^{- 2}

and moment of inertia

5 \times 10^{- 6} kg m^{2} .

If it performs

10

complete oscillations in

5

seconds then the magnitude of the magnetic field is ____

mT

[Take

π^{2}

9.85]

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A rectangular coil of length

0.12 m

and width

0.1 m

having

50

turns of wire is suspended vertically in a uniform magnetic field of strength

0.2

W e b e r / m^{2}

. The coil carries a current of

2 A

. If the plane of the coil is inclined at an angle of

30^{o}

with the direction of the field, the torque required to keep coil in stable equilibrium will be:

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

Work done in displacing a Magnetic Dipole of magnetic moment

M

, (Bar Magnet) in Uniform Magnetic Field

B

from an angle

θ_{1}

θ_{2}

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A bar magnet of magnetic moment

5 A m^{2}

is placed in a uniform magnetic induction

3 \times 10^{- 5} T .

If each pole of a magnet experiences a force of

2.5 \times 10^{- 4} N

then the magnetic length of the magnet is

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

The rectangular coil of area $A$ is in a field $B .$ Find the torque about the $Z$ -axis when the coil lies in the position shown and carries a current $I .$

Question Image

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A current-carrying coil is subjected to a uniform magnetic field. The coil will orient so that its plane becomes

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Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A bar magnet having a magnetic moment of

2.0 \times 10^{5} J T^{- 1}

, is placed along the direction of uniform magnetic field of magnitude

B = 14 \times 10^{- 5} T

. The work done in rotating the magnet slowly through

60 °

from the direction of field is

EASY

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A circular current loop of magnetic moment

M

is in an arbitrary orientation in an external uniform magnetic field

\vec{B}

. The work done to rotate the loop by

30 °

about an axis perpendicular to its plane is

MEDIUM

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A bar magnet is hung by a thin cotton thread in a uniform horizontal magnetic field and is in equilibrium state. The energy required to rotate it by

60^{o}

W

. Now, the torque required to keep the magnet in this new position is

HARD

Physics>Electricity and Magnetism>Magnetic Effect of Current>Current Carrying Loop in External Magnetic Field

A rectangular loop of sides $10 cm$ and $5 cm$ , carrying a current $I$ of $12 A$ , is placed in different orientations as shown in the figure below.
(a) Question Image (b)

(c) (d)

If there is a uniform magnetic field of $0.3 T$ in the positive $z$ direction, in which orientations the loop would be in $(i)$ stable equilibrium and $(ii)$ unstable equilibrium?

A magnet of magnetic moment M is situated with its axis along the direction of a magnetic field of strength B .The work done in rotating it by an angle of 180° will be :-

Important Questions on Magnetic Effect of Current

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A magnet of magnetic moment $M$ is situated with its axis along the direction of a magnetic field of strength $B .$ The work done in rotating it by an angle of $180 °$ will be :-