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An electron in an atom revolves around the nucleus in an orbit of radius $0.5 Å$ . Calculate the equivalent magnetic moment, if the frequency of revolution of electron is $10^{10} MHz$ . ( $e = 1.6 \times 10^{- 19} C$ )

Important Questions on Moving Charges and Magnetism

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

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>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

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:

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

The dipole moment of a circular loop carrying a current I, is m and the magnetic field at the centre of the loop is

B_{1}

. When the dipole moment is doubled by keeping the current constant, the magnetic field at the centre of the loop is

B_{2}

. The ratio

\frac{B_{1}}{B_{2}}

is:

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

Torque acting on a rectangular coil carrying current

i

situated parallel to magnetic field of induction

B

, having the number of turns

n

and area

A

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

Obtain an expression for magnetic moment of an orbital electron.

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

Following figures show the arrangement of bar magnets in different configurations. Each magnet has magnetic dipole

\vec{m} .

Which configuration has highest net magnetic dipole moment?

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

The magnetic moment of electron due to orbital motion is proportional to (

n

= principal quantum numbers)

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

The ratio of angular momentum

L

to the atomic dipole moment

μ_{i}

for hydrogen like atoms and ions is

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

A charge

q

is spread uniformly over an insulated loop of radius

r

. If it is rotated with an angular velocity

ω

with respect to normal axis then magnetic moment of the loop is:

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

The magnetic moments associated with two closely wound circular coils

A

and

B

of radius

r_{A} = 10 cm and r_{B} = 20 cm

respectively are equal if: (Where

N_{A}, I_{A} and N_{B}, I_{B}

are number of turn and current of

A and B

respectively)

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

An iron rod of volume

10^{- 3} m^{3}

and relative permeability

1000

is placed as core in a solenoid with

10 turns {cm}^{- 1}

. If a current of

0.5 A

is passed through the solenoid, then the magnetic moment of the rod will be :

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

Magnetic moment of revolving electron of charge

e

and mass

m

in terms of angular momentum

L

of electron is

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

A wire of length

L

metre carrying a current of

I

ampere is bent in the form of a circle. Its magnetic moment is,

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

A square loop is carrying a steady current

I

and the magnitude of its magnetic dipole moment is

m

. If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be:

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

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

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

The ratio of the magnetic field at the centre of a current-carrying circular coil to magnetic moment is $x$ . If the current and the radius both are doubled. The new ratio will become

EASY

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

In a permanent magnet at room temperature

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

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?

HARD

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

Derive an expression for magnitude of magnetic dipole moment of a revolving electron. A circular coil of

300

turns and diameter

14 cm

carries a current of

15 A

. Calculate the magnitude of the magnetic dipole moment associated with the coil.

MEDIUM

Physics>Electricity and Magnetism>Moving Charges and Magnetism>Torque on Current Loop, Magnetic Dipole

A proton is revolving on a circular path of radius

2 mm

with frequency

10 Hz

. Magnetic dipole moment associated with proton is

An electron in an atom revolves around the nucleus in an orbit of radius 0.5 Å. Calculate the equivalent magnetic moment, if the frequency of revolution of electron is 1010 MHz. (e=1.6×10-19 C)

Important Questions on Moving Charges and Magnetism

Learn and Prepare for any exam you want !

An electron in an atom revolves around the nucleus in an orbit of radius $0.5 Å$ . Calculate the equivalent magnetic moment, if the frequency of revolution of electron is $10^{10} MHz$ . ( $e = 1.6 \times 10^{- 19} C$ )