MCQs of Moving Charges & Magnetism

Moving Charges & Magnetism MCQs

MCQs of Moving Charges & Magnetism

Showing 101 to 110 out of 123 Questions

101.

An electron moves with a constant speed V along a circle of radius r. Its magnetic moment will be _____ . (e is electron's charge)

(a)	evr
(b)	$\frac{1}{2} e v r$
(c)	πr²ev
(d)	2πrev

102.

A rectangular coil 20 cm × 20 cm has 100 turns and carries a current of 1 A. It is placed in a uniform magnetic field B = 0.5 T with the direction of magnetic field parallel to the plane of the coil. Find the magnitude of the torque required to hold this coil in the position.

(a)	zero
(b)	200 Nm
(c)	2 Nm
(d)	10 Nm

103.

A current carrying small loop behaves like a small magnet. If A be its area and M its magnetic moment, then what will be the current in the loop ?

(a)	$\frac{M}{A}$
(b)	$\frac{A}{M}$
(c)	MA
(d)	A²M

104.

A voltmeter has a resistance of G ohm and range V volt. What is the value of resistance used in series to convert it into a voltmeter of range nV volt ?

(a)	nG
(b)	(n-1)G
(c)	$\frac{G}{n}$
(d)	$\frac{G}{(n - 1)}$

105.

which of the following statements is wrong ?

(a)	Voltmeter should have high resistance.
(b)	Ammeter should have low resistance.
(c)	Ammeter is placed in parallel across the conductor in a circuit.
(d)	Voltmeter is placed in parallel across the conductor in a circuit.

106.

A galvanometer of resistance 25 Ω giving full scale deflection for a current of 10 mA. is to be changed into a voltmeter of range 100 V by connecting a resistance of 'R' in series with galvanometer. What is the value of resistance R in Ω ?

(a)	10,000
(b)	10,025
(c)	975
(d)	9975

107.

A steady current I goes through a wire loop PQR having shape of a right angled triangle with PQ=3x, PR=4x and QR=5x. If the magnitude of the magnetic field at P due to this loop is

k \frac{π_{0} I}{48 π x}

, then find the value of k _____.

(a)	8
(b)	3
(c)	7
(d)	None of these

108.

A particle carrying a charge equal to 100 time the charge on an electron is rotating per second in a circular path of radius 0.8 metre. Find the value of the magnetic field produced at the centre. (μ₀= permeability for vacuum)

(a)	$\frac{10^{- 7}}{μ_{0}}$
(b)	10^-17μ₀T
(c)	10^-6μ₀T
(d)	10^-7μ₀T

109.

Two concentric coil of ten turns each are situated in the same plane. Their radius are 20 cm and 40 cm and they carry respectively 0.2 A and 0.3 A current in opposite direction. What is the magnetic field in weber/m² at the centre ?

(a)	$\frac{35}{4} μ_{0}$
(b)	$\frac{μ_{0}}{80}$
(c)	$\frac{7}{80} μ_{0}$
(d)	$\frac{5}{4} μ_{0}$

110.

A long straight wire of radius 'a' carries a steady current I. The currrent is uniform distributed across its cross-section. What is the ratio of the magnetic field at

\frac{a}{2}

and 2a ?

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

Showing 101 to 110 out of 123 Questions