A 2 amp current is flowing through two different small circular copper coils having radii 1:2. The ratio of their respective magnetic moments will be

(1). 4:1
(2). 1:4
(3). 1:2
(4). 2:1

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

In a uniform magnetic field of 0.049T, a magnetic needle performs 20 complete oscillations in 5 seconds as shown. The moment of inertia of the needle is \(9.8×10^{−6} kgm^2\). If the magnitude of magnetic moment of the needle is \(x×10^{−5} Am^2\), then the value of 'x ' is :


(1). \(5π^2\)
(2). \(128π^2\)
(3). \(50π^2\)
(4). \(1280π^2\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

In the above diagram, a strong bar magnet is moving towards solenoid-2 from solenoid-1. The direction of induced current in solenoid-1 and that in solenoid-2, respectively, are through the directions:

(1). AB and DC
(2). BA and CD
(3). AB and CD
(4). BA and DC

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

Match List-I with List-II.

Choose the correct answer from the options given below.

(1). A-II, B-III, C-IV, D-I
(2). A-II, B-I, C-III, D-IV
(3). A-III, B-II, C-I, D-IV
(4). A-IV, B-III, C-II, D-I

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

A sheet is placed on a horizontal surface in front of a strong magneticpole. A force is needed to:
A. hold the sheet there if it is magnetic.
B. hold the sheet there if it is non-magnetic.
C. move the sheet away from the pole with uniform velocity if it is conducting.
D. move the sheet away from the pole with uniform velocity if it is both,non-conducting and non-polar.
Choose the correct statement(s) from the options given below:

(1). B and D only
(2). A and C only
(3). A, C and D only
(4). C only

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

An iron bar of length L has magnetic moment M. It is bent at the middle of its length such that the two arms make an angle \(60^ \circ\) with each other. The magnetic moment of this new magnet is :

(1). \(M\)
(2). \(\frac{M}{2}\)
(3). \(2M\)
(4). \(\frac{M}{\sqrt{3}}\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

The dimensions [\(M LT^{−2}A^{−2}\)] belong to the

(1). Magnetic flux
(2). Self inductance
(3). Magnetic permeability
(4). Electric permittivity

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

A long solenoid of radius 1mm has 100 turns per mm. If 1 A current flows in the solenoid, the magnetic field strength at the centre of the solenoid is

(1). \(6.28 \times 10^{−2}\,T\)
(2). \(12.56 \times 10^{−2}\,T\)
(3). \(12.56 \times 10^{−4}\,T\)
(4). \(6.28 \times 10^{−4}\,T\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

A uniform conducting wire of length \(12\,a\) and resistance 'R' is wound up as a current carrying coil in the shape of,
(i) an equilateral triangle of side 'a'.
(ii) a square of side 'a'.
The magnetic dipole moments of the coil in each case respectively are

(1). \(\sqrt{3}\, Ia^2\) and \(3\, I_a^2\)
(2). \(3\, Ia^2\) and \(Ia^2\)
(3). \(3\, Ia^2\) and \(4\, Ia^2\)
(4). \(4\, Ia^2\) and \(3\, Ia^2\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

An iron rod of susceptibility \(599\) is subjected to a magnetising field of \(1200\,A\,m^{−1}\). The permeability of the material of the rod is :\(\mu_0\, =\, 4\, \pi \times 10^{−7}\,T\, m\,A^{−1}\)

(1). \(8.0 \times 10^{−5}\,T\, m\,A^{−1}\)
(2). \(2.4\pi \times 10^{−5}\,T\, m\,A^{−1}\)
(3). \(2.4\pi \times 10^{−7}\,T\, m\,A^{−1}\)
(4). \(2.4\pi \times 10^{−4}\,T\, m\,A^{−1}\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

At a point A on the earth's surface the angle of dip, \(\delta \, =\, +25^\circ\). At a point B on the earth's surface the angle of dip, \(\delta \, =\, -25^\circ\). We can interpret that

(1). A and B are both located in the southern hemisphere.
(2). A and B are both located in the northern hemisphere.
(3). A is located in the southern hemisphere and B is located in the northern hemisphere.
(4). A is located in the northern hemisphere and B is located in the southern hemisphere.

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

A thin diamagnetic rod is placed vertically between the poles of an electromagnet. When the current in the electromagnet is switched on, then the diamagnetic rod is pushed up, out of the horizontal magnetic field. Hence the rod gains gravitational potential energy. The work required to do this comes from

(1). The current source
(2). The magnetic field
(3). The lattice structure of the material of the rod
(4). The induced electric field due to the changing magnetic field

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

If \(θ_1\) and \(θ_2\) be the apparent angles of dip observed in two vertical planes at right angles to each other, then the true angle of dip \(\theta\) is given by

(1). \(tan^2θ = tan^2θ_1 + tan^2θ_2\)
(2). \(cot^2θ = cot^2θ_1 − cot^2θ_2\)
(3). \(tan^2θ = tan^2θ_1 − tan^2θ_2\)
(4). \(cot^2θ = cot^ 2θ_1 + cot^2θ_2\)

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

A 250 turn rectangular coil of length 2.1 cm and width 1.25 cm carries a current of 85 µA and subjected to a magnetic field of strength 0.85 T. Work done for rotating the coil by 180° against the torque is

(1). 4.55 µJ
(2). 2.3 µJ
(3). 1.15 µJ
(4). 9.1 µJ

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02

The magnetic susceptibility is negative for

(1). ferromagnetic material only
(2). paramagnetic and ferromagnetic materials
(3). diamagnetic material only
(4). paramagnetic material only

Number of Attempts: 2

Correct Attempts: 1

Time Taken: 00:04

Average Time: 00:02