MCQs of Moving Charges & Magnetism

Moving Charges & Magnetism MCQs

MCQs of Moving Charges & Magnetism

Showing 21 to 30 out of 123 Questions

21.

Two concentric rings are kept in the same plane. Number of turns in both the rings is 20. Their radii are 40 cm and 80 cm and they carry electric currents of 0.4 A and 0.6 A respectively, in mutually opposite directions. The magnitude of the magnetic field produced at their centre is _____ T.

(a)	4μ₀
(b)	2μ₀
(c)	$\frac{10}{4}$ μ₀
(d)	$\frac{5}{4}$ μ₀

22.

A particle of mass m has an electric charge q. This particle is accelerated through a potential difference V and then entered normally in a uniform magnetic field B. It performs a circular motion of radius R. The ratio of its charge to the mass

(\frac{q}{m})

is = _____ [

(\frac{q}{m})

is also called specific charge.]

(a)	$\frac{2 V}{B^{2} R^{2}}$
(b)	$\frac{V}{2 BR}$
(c)	$\frac{VB}{2 R}$
(d)	$\frac{m V}{BR}$

23.

A proton, a deuteron ion and an α-particle of equal kinetic energy perform circular motion normal to a uniform magnetic field B. If the radii of their paths are r_p, r_d and r_α respectively then _____ [Here, q_d = q_p, m_d = 2m_p]

(a)	r_α = r_p < r_d
(b)	r_α = r_d > r_p
(c)	r_α > r_d > r_p
(d)	r_α = r_d = r_p

24.

An electron performs circular motion of radius r, perpendicular to a uniform magnetic field B. The kinetic energy gained by this electron in half the revolution is _____

(a)	$\frac{1}{2} m v^{2}$
(b)	$\frac{1}{4} m v^{2}$
(c)	zero
(d)	$π r B e v$

25.

A particle of charge q and mass m moves on a circular path of radius r in a plane inside and normal to a uniform magnetic field B. The time taken by this particle to complete one revolution is _____ .

(a)	$\frac{2 π m q}{B}$
(b)	$\frac{2 π q^{2} B}{m}$
(c)	$\frac{2 π q B}{m}$
(d)	$\frac{2 π m}{B q}$

26.

A long wire carries a steady current. When it is bent in a circular form, the magnetic field at its centre is B. Now if this wire is bent in a circular loop of n turns, what is the magnetic field at its centre ?

(a)	nB
(b)	n²B
(c)	2nB
(d)	2n²B

27.

A conducting wire of 1 m length is used to form a circular loop. If it carries a current of 1 ampere, its magnetic moment will be _____ Am²

(a)	2π
(b)	$\frac{π}{2}$
(c)	$\frac{π}{4}$
(d)	$\frac{1}{4 π}$

28.

1 T = _____ gauss.

(a)	10⁷
(b)	10⁴
(c)	10^-4
(d)	10^-8

29.

At each of the two ends of a rod length 2r, a particle of mass m and charge q is attached. If this rod is rotated about its centre with angular speed of ω, the ratio of its magnetic dipole moment to the total angular momentum of this particle is _____ .

(a)	$\frac{q}{2 m}$
(b)	$\frac{q}{m}$
(c)	$\frac{2 q}{m}$
(d)	$\frac{q}{π m}$

30.

There are 100 turns per cm length in a very long solenoid. It carries a current of 5 A. The magnetic field at its centre on the axis is _____ T.

(a)	3.14 x 10^-2
(b)	6.28 x 10^-2
(c)	9.42 x 10^-2
(d)	12.56 x 10^-2

Showing 21 to 30 out of 123 Questions