MCQs of Moving Charges & Magnetism

Moving Charges & Magnetism MCQs

MCQs of Moving Charges & Magnetism

Showing 81 to 90 out of 123 Questions

81.

The ratio of periods of α-particle and proton moving on cirular path, in uniform magnetic field is _____.

(a)	2:1
(b)	4:1
(c)	1:2
(d)	1:4

82.

Two concentric rings are kept in the same plane. Number of turns in each ring is 25. Their radii are 50 cm and 200 cm and they carry electric currents of 0.1 A and 0.2 A respectively, in mutually opposite direction. The magnitude of the magnetic field produced at their centre is _____ T.

(a)	4μ₀
(b)	$\frac{10}{4} μ_{0}$
(c)	2μ₀
(d)	$\frac{5}{4} μ_{0}$

83.

Equal currents are passing through two very long and straight parallel wires in the same direction. they will _____ .

(a)	repel each other
(b)	lean towards each other
(c)	attract each other
(d)	neither attract nor repel each other

84.

A galvanometer of resistance 50 Ω is connected to a battery of 8 V along with resistance of 3950 Ω in series. A full scale deflection of 30 division is obtained in the galvanometer. In order to reduce this deflection to 15 division, the resistance in series should be _____ Ω.

(a)	7900
(b)	2000
(c)	1950
(d)	7950

85.

A length L of wire carries a steady current I. It is bent first to form a circular plane coil of one turn. The same length is now bend more sharply to give a double loop of smaller radius. What is the magnetic field at the centre caused by the same current ?

(a)	A quarter of its first value
(b)	Unaltered
(c)	Four time of its first value
(d)	A half of its first value

86.

A horizontal over head power line is at a height of 4 m from the ground and carries a current of 100 A from east to west. What is the magnetic field directly below it on the ground ?

(a)	5×10^-6 T northward
(b)	5×10^-6 T southward
(c)	2.5×10^-7 T northward
(d)	2.5×10^-6 T southward

87.

A helium nucleus makes a full rotation in a circle of radius 0.8 meter in two seconds. What will be the value of the magnetic field B at the centre of the circle ?

(a)	$\frac{10^{- 19}}{μ_{0}}$
(b)	$10^{- 19} μ_{0}$
(c)	$2 \times 10^{- 10} μ_{0}$
(d)	$\frac{2 \times 10^{- 10}}{μ_{0}}$

88.

The strength of the magnetic field at a perpendicular distance r near a long straight current carrying wire is B. What will be the field at a perpendicular distance of

\frac{r}{2}

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

89.

A circular coil of radius R carries an electric current. The magnetic field due to the coil at a point on the axis of the coil located at a distance r from the centre of the coil, such that r>>R. then B is proportional to _____.

(a)	$\frac{1}{r}$
(b)	$\frac{1}{r^{\frac{3}{2}}}$
(c)	$\frac{1}{r^{2}}$
(d)	$\frac{1}{r^{3}}$

90.

A current I flows along the length of an infinitely long, straight and thin-walled pipe. Then _____ .

(a)	the magnetic field at all point inside the pipe is the same but not zero
(b)	the magnetic field at any point inside the pipe is zero
(c)	the magnetic field is zero only on the axis of the pipe
(d)	the magnetic field is different at different point inside

Showing 81 to 90 out of 123 Questions