MCQs of Magnetism and Matter

Magnetism and Matter MCQs

MCQs of Magnetism and Matter

Showing 41 to 50 out of 145 Questions

41.

A short bar magnet has a length 2l and a magnetic moment 10 A m². Find the magnetic field at a distance of z = 0.1 m from its centre on the axial line. Here, l is negligible as compared to z

(a) 4 × 10^-3 T

(b) 1 × 10^-3 T

(c) 3 × 10^-3 T

(d) 2 × 10^-3 T

42.

A short bar magnet experiences a torque of magnitude 0.64 J when it is placed in a uniform magnetic field of 0.32 T, making an angle 30º with the direction of the field. The magnetic moment of the magnet is _____ .

(a)	2 Am²
(b)	6 Am²
(c)	4 Am²
(d)	None of the above

43.

The magnetic field due to short bar magnet of magnetic dipole moment m and length 2l, on the axis at a distance z (where z >> l) from the centre of the magnet is given be formula _____ .

(a) $\frac{μ_{0} m}{4 {πz}^{3}} \hat{m}$

(b) $\frac{2 μ_{0} m}{4 {πz}^{3}} \hat{m}$

(c) $\frac{4 π m}{μ_{0} z^{3}} \hat{m}$

(d) $\frac{μ_{0} m}{2 {πz}^{3}} \hat{m}$

44.

A magnetic wire of dipole moment 4 π A m² is bent in the form of semi-circle. The new magnetic moment is _____ .

(a)	4 π A m²
(b)	8 π A m²
(c)	4 A m²
(d)	None of the above

45.

A bar magnet is placed in the position of stable equilibrium in a uniform magnetic field of induction B. If it is rotated through an angle 180º, then the work done is _____ . (m = Magnetic dipole moment of bar magnet)

(a) $m B$

(b) $2 m B$

(c) $\frac{m B}{2}$

(d) zero

46.

If an electron of charge e moves in a circular orbit of radius r around the nucleus at a frequency f, then what is the magnetic moment associated with the orbital motion of electron ?

(a) $π f {er}^{2}$

(b) $\frac{π f r^{2}}{e}$

(c) $\frac{π f e}{r^{2}}$

(d) $\frac{π e r^{2}}{f}$

47.

A bar magnet is oscillating in Earth's magnetic field with periodic time T. If a similar magnet with same mass and volume has magnetic dipole moment, which is 9 times that of this magnet, then the periodic time will be _____ .

(a) $\frac{T}{2}$

(b) $\frac{T}{3}$

(c) $\frac{T}{9}$

(d) $\frac{T}{6}$

48.

A domain in a ferromagnetic substance is in the form of cube of side length 2 μm. If is contains 4 × 10¹⁰ atoms and each atomic dipole moment of 16× 10^-24 Am², then magnetization of the domain is _____ Am^{-1^.}

(a)	64 × 10⁴
(b)	3.6 × 10⁴
(c)	7.2 × 10⁴
(d)	8 × 10⁴

49.

The dimensional formula of magnetic flux is _____ .

(a)	$M^{1} L^{2} T^{- 3} A^{- 1}$
(b)	$M^{- 1} L^{- 2} T^{2} A^{1}$
(c)	$M^{1} L^{2} T^{- 2} A^{- 1}$
(d)	$M^{1} L^{3} T^{- 2} A^{- 1}$

50.

The magnetic susceptibility of a paramagnetic material is 1.0 × 10^-5 at 27ºC temperature. Then, at what temperature , its magnetic susceptibility would be 1.5 × 10^-5 ?

(a)	15ºC
(b)	-73ºC
(c)	200ºC
(d)	-18ºC

Showing 41 to 50 out of 145 Questions