The magnetic moment of a current-loop is 2 .1 × 10 - 25 Am 2 . Find the magnetic field on the axis of the loop at a distance of 1 . 0 A o from the loop.

Given: Magnetic moment of current-loop, M = 2 .1 × 10 - 25 A m 2 Distance from loop, r = 1 .0 Å = 10 - 10 m The current loop is a short magnetic dipole. Hence, B a x i a l = μ 0 4 π . 2 M r 3 = 10 - 7 × 2 × 2 .1 × 10 - 25 1 .0 × 10 - 10 3 = 4 .2 × 10 - 2 T

Two short magnets of magnetic moments a and b of magnetic moments 32 A m 2 and 27 A m 2 are placed on a table, as shown in figure. Find the magnitude and direction of the magnetic field produced. These magnets at point P situated at the equatorial lines of both the magnets at distances 40 cm and 30 cm respectively from the centres of the two magnets.

The magnetic moment of the magnet a , m 1 = 32 Am 2 The magnetic moment of the magnet b , m 2 = 27 Am 2 The distance of point P from the magnet a , r 1 = 40 cm = 0 .4 m The distance of point P from the magnet b , r 2 = 30 cm = 0 .3 m As shown in the figure, the point P lies on the equatorial line of both the magnets a and b . We know the magnetic field due to bar magnet along its equatorial line is B e q u a = μ 0 4 π . m r 3 ∴ B a = μ 0 4 π . m 1 r 1 3 = 10 - 7 × 32 0 .40 3 = 0 .5 × 10 - 4 T B b = μ 0 4 π . m 2 r 2 3 = 10 - 7 × 27 0 .30 3 = 10 - 4 T The two fields are perpendicular to each other as shown in the figure. So the resultant field at point P is B = B a 2 + B b 2 = 10 - 4 0 .5 2 + 1 2 = 1 .12 × 10 - 4 T If the field B makes an angle θ with the direction of B b , then tan θ = B a B b = 0 .5 × 10 - 4 10 - 4 = 0 .5 or θ = 26 .57 o

EASY

12th CBSE

IMPORTANT

Earn 100

A bar magnet has a length of $8 cm$ . The magnetic field at a point at a distance of $3 cm$ from the centre in the broad-side on position is found to be $4 \times 10^{- 6} T$ . Calculate the pole strength of the magnet.

Important Questions on Magnetism

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>Problems For Practice>Q 4

The magnetic moment of a current-loop is

2 .1 \times 10^{- 25} {Am}^{2}

. Find the magnetic field on the axis of the loop at a distance of

1.0 \overset{o}{A}

from the loop.

EASY

12th CBSE

IMPORTANT

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

If the earth's magnetic field has a magnitude of

3 .4 \times 10^{- 5} T

at the magnetic equator of the earth, what would be its value at the magnetic poles of the earth?

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>Problems For Practice>Q 6

The intensities of magnetic field at two points on the axis of a bar magnet at distances

0.1 m

and

0.2 m

from its middle point are in the ratio

12.5 : 1

. Calculate the distance between the poles of the magnet.

MEDIUM

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>Problems For Practice>Q 7

Two short magnets

a

and

b

of magnetic moments

0 .108 A m^{2}

and

0 .192 A m^{2}

are placed along mutually perpendicular straight lines meeting at a point P. Find the magnitude and direction of magnetic field at point P, if it lies at distances

30 cm

and

60 cm

respectively from the centres of the two magnets.

HARD

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>Problems For Practice>Q 8

Two short magnets of magnetic moments $a$ and $b$ of magnetic moments $32 A m^{2}$ and $27 A m^{2}$ are placed on a table, as shown in figure. Find the magnitude and direction of the magnetic field produced.

Question Image

These magnets at point $P$ situated at the equatorial lines of both the magnets at distances $40 cm$ and $30 cm$ respectively from the centres of the two magnets.

EASY

12th CBSE

IMPORTANT

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

A short bar magnet of magnetic moment

0 .9 J T^{- 1}

is placed with its axis at

30 °

a uniform magnetic field. It experiences a torque of

0.063 Nm

. Calculate the magnitude of the magnetic field.

EASY

12th CBSE

IMPORTANT

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

A short bar magnet of magnetic moment

0 .9 J T^{- 1}

is placed with its axis at

30 °

a uniform magnetic field. It experiences a torque of

0.063 Nm

. In which orientation will the bar magnet be in stable equilibrium, in the magnetic field?

EASY

12th CBSE

IMPORTANT

New Simplified Physics (Vol 1) For Class 12>Chapter 5 - Magnetism>Problems For Practice>Q 2

Calculate the magnitude of the torque required to hold a bar magnet of magnetic moment

200 {Am}^{2}

along a direction making an angle of

30 °

with the direction of a uniform magnetic field of

0.36 G

A bar magnet has a length of 8 cm. The magnetic field at a point at a distance of 3 cm from the centre in the broad-side on position is found to be 4×10-6 T. Calculate the pole strength of the magnet.

Important Questions on Magnetism

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A bar magnet has a length of $8 cm$ . The magnetic field at a point at a distance of $3 cm$ from the centre in the broad-side on position is found to be $4 \times 10^{- 6} T$ . Calculate the pole strength of the magnet.