Explore topic-wise MCQs in Physics.

This section includes 24 Mcqs, each offering curated multiple-choice questions to sharpen your Physics knowledge and support exam preparation. Choose a topic below to get started.

1.

A moving coil galvanometer has a coil with 175 turns and area 1 cm2. It uses a torsion band of torsion constant 10-6 N-m/rad. The coil is placed in a magnetic field B parallel to its plane. The coil deflects by 1° for a current of 1 mA. The value of B (in Tesla) is approximately:

A. 10-4
B. 10-2
C. 10-1
D. 10-3
Answer» E.
2.

A paramagnetic material has 1028 atoms/m3. Its magnetic susceptibility at temperature 350 K is 2.8 × 10-4. Its susceptibility at 300 K is

A. 3.726 × 10-4
B. 3.672 × 10-4
C. 2.672 × 10-4
D. 3.267 × 10-4
Answer» E.
3.

A galvanometer having a resistance of 20 Ω and 30 divisions on both sides has figure of merit 0.005 ampere/division. The resistance that should be connected in series such that it can be used as a voltmeter up to 15 volt is

A. 100 Ω
B. 125 Ω
C. 120 Ω
D. 80 Ω
Answer» E.
4.

Charges -q and +q located at A and B, respectively, constitute an electric dipole. Distance AB = 2a, O is the midpoint of the dipole and OP is perpendicular to AB.A charge Q is placed at P, where OP = y and y 2a. The charge Q experiences an electrostatic force F.If Q is now moved along the equatorial line to P' such that \(OP' = \left( {\frac{y}{3}} \right),\) the force on Q will close to \(\left( {\frac{y}{3} \gg 2a} \right)\)

A. \(\frac{F}{3}\)
B. 3F
C. 9F
D. 27F
Answer» E.
5.

A circular coil having N turns and radius r carries a current I. It is held in the XZ plane in a magnetic field \(B\hat i\). The torque on the coil due to the magnetic field is:

A. \(\frac{{{\rm{B}}{{\rm{r}}^2}{\rm{I}}}}{{\pi {\rm{N}}}}\)
B. Bπr2 IN
C. \(\frac{{{\rm{B}}\pi {{\rm{r}}^2}{\rm{I}}}}{{\rm{N}}}\)
D. Zero
Answer» C. \(\frac{{{\rm{B}}\pi {{\rm{r}}^2}{\rm{I}}}}{{\rm{N}}}\)
6.

A solid sphere of mass 'M' and radius 'a' is surrounded by a uniform concentric spherical shell of thickness 2a and mass 2M. The gravitational field at distance '3a' from the centre will be:

A. \(\frac{{2{\rm{GM}}}}{{9{{\rm{a}}^2}}}\)
B. \(\frac{{{\rm{GM}}}}{{9{{\rm{a}}^2}}}\)
C. \(\frac{{{\rm{GM}}}}{{3{{\rm{a}}^2}}}\)
D. \(\frac{{2{\rm{GM}}}}{{3{{\rm{a}}^2}}}\)
Answer» D. \(\frac{{2{\rm{GM}}}}{{3{{\rm{a}}^2}}}\)
7.

One of the two identical conducting wires of length L is bent in the form of a circular loop and the other one into a circular coil of N identical turns. If the same current is passed in both, the ratio of the magnetic field at the central of the loop (BL) to that at the centre of the coil (BC), i.e. \(\frac{{{{\rm{B}}_{\rm{L}}}}}{{{{\rm{B}}_{\rm{C}}}}}\) will be:

A. N
B. \(\frac{1}{{\rm{N}}}\)
C. N2
D. \(\frac{1}{{{{\rm{N}}^2}}}\)
Answer» E.
8.

A moving coil galvanometer has resistance 50 Ω and it indicates full deflection at 4 mA current. A voltmeter is made using this galvanometer and a 5 kΩ resistance. The maximum voltage, that can be measured using this voltmeter, will be close to:

A. 40 V
B. 15 V
C. 20 V
D. 10 V
Answer» D. 10 V
9.

If a charged particle (+q) is projected with a certain velocity parallel to the magnetic field, then it will

A. Trace helical path
B. Trace circular path
C. Continue its motion without any change
D. Come to rest instantly
Answer» D. Come to rest instantly
10.

A galvanometer whose resistance is 50 Ω has 25 divisions in it. When a current of 4 × 10-4A passes through it, its needle (pointer) deflects by one division. To use this galvanometer as a voltmeter of range 2.5 V, it should be connected to a resistance of

A. 250 Ω
B. 6200 Ω
C. 200 Ω
D. 6250 Ω
Answer» D. 6250 Ω
11.

An infinitely long current carrying wire and a small current carrying loop are in the plane of the paper as shown. The radius of the loop is ‘a’ and distance of its center from the wire is d (d >> a). If the loop applies a force ‘F’ on the wire then:

A. F = 0
B. \({\rm{F}} \propto \left( {\frac{{\rm{a}}}{{\rm{d}}}} \right)\)
C. \({\rm{F}} \propto \left( {\frac{{{{\rm{a}}^2}}}{{{{\rm{d}}^3}}}} \right)\)
D. \({\rm{F}} \propto {\left( {\frac{{\rm{a}}}{{\rm{d}}}} \right)^2}\)
Answer» E.
12.

A bar magnet is demagnetized by inserting it inside a solenoid of length 0.2 m, 100 turns, and carrying a current of 5.2 A. The Coercivity of the bar magnet is:

A. 285 A/m
B. 2600 A/m
C. 520 A/m
D. 1200 A/m
Answer» C. 520 A/m
13.

An insulating thin rod of length l has a linear charge density \(\rho \left( x \right) = {\rho _0}\left( {\frac{x}{l}} \right)\) on it. The rod is rotated about an axis passing through the origin (x = 0) and perpendicular to the rod. If the rod makes n rotations per second, then the time averaged magnetic moment of the rod is

A. nρl3
B. πnρl3
C. \(\frac{\pi }{3}n\rho {l^3}\)
D. \(\frac{\pi }{4}n\rho {l^3}\)
Answer» E.
14.

A moving coil galvanometer allows a full-scale current of 10-4 A. A series resistance of 2 MΩ is required to convert the above galvanometer into a voltmeter of range 0-5 V. Therefore, the value of shunt resistance required to convert the above galvanometer into an ammeter of range 0-10 mA is:

A. 500 Ω
B. 100 Ω
C. 200 Ω
D. None of the above
Answer» E.
15.

A paramagnetic substance in the form of a cube with sides 1 cm has a magnetic dipole moment of 20 × 10-6 J/T when a magnetic intensity of 60 × 103 A/m is applied. Its magnetic susceptibility is

A. 3.3 × 10-4
B. 3.3 × 10-2
C. 4.3 × 10-2
D. 2.3 × 10-2
Answer» B. 3.3 × 10-2
16.

A square loop is carrying a steady current I and the magnitude of its magnetic dipole moment is m. If this square loop is changed to a circular loop and it carries the same current, the magnitude of the magnetic dipole moment of circular loop will be:

A. \(\frac{{\rm{m}}}{{\rm{\pi }}}\)
B. \(\frac{{3{\rm{m}}}}{{\rm{\pi }}}\)
C. \({\rm{\;}}\frac{{2{\rm{m}}}}{{\rm{\pi }}}\)
D. \({\rm{\;}}\frac{{4{\rm{m}}}}{{\rm{\pi }}}\)
Answer» E.
17.

Corkscrew rule for the direction of magnetic field in relation to the direction of current conducted by the conductor is given by

A. Ampere
B. Orsted
C. Max Planck
D. None of them
Answer» E.
18.

As shown in the figure, two infinitely long, identical wires are bent by 90° and placed in such a way that the segments LP and QM are along the X -axis, while segments PS and QN are parallel to the Y-axis. If OP = OQ = 4 cm, and the magnitude of the magnetic field at O is 10-4 T and the two wires carry equal currents (see figure), the magnitude of the current in each wire and the direction of the magnetic field at O will be (Take, μ0 = 4π × 10-7 NA-2)

A. 40 A, perpendicular out of the page
B. 20 A, perpendicular into the page
C. 20 A, perpendicular out of the page
D. 40 A, perpendicular into the page
Answer» C. 20 A, perpendicular out of the page
19.

A conducting circular loop made of a thin wire, has area 3.5 × 10-3 m2 and resistance 10 Ω. It is placed perpendicular to a time dependent magnetic field B(t) = (0.4T)sin(50πt). The field is uniform in space. Then the net charge flowing through the loop during t = 0 s and t = 10 ms is close to:

A. 14 mC
B. 7 mC
C. 21 mC
D. 6 mC
Answer» B. 7 mC
20.

For a uniformly charged ring of radius R, the electric field on its axis has the largest magnitude at a distance h from its center. Then value of h is:

A. \(\frac{{\rm{R}}}{{\sqrt 5 }}\)
B. \(\frac{{\rm{R}}}{{\sqrt 2 }}\)
C. R
D. \({\rm{R}}\sqrt 2 \)
Answer» C. R
21.

A current loop, having two circular arcs joined by two radial lines is shown in the figure. It carries a current of 10 A. The magnetic field at point O will be close to:

A. 1.0 × 10-7 T
B. 1.5 × 10-7 T
C. 1.5 × 10-5 T
D. 1.0 × 10-5 T
Answer» E.
22.

A 10m long horizontal wire extends from North-East to South-West. It is falling with a speed of 5.0 ms-1 at right angles to the horizontal component of the earth's magnetic field of 0.3 × 10-4 Wb/m2. The value of the induced emf in wire is

A. 1.5 × 10-3 V
B. 1.1 × 10-3 V
C. 0.3 × 10-3 V
D. 2.5 × 10-3 V
Answer» C. 0.3 × 10-3 V
23.

A particle having the same charge as of electron moves in a circular path of radius 0.5 cm under the influence of a magnetic field of 0.5 T. If an electric field of 100 V/m makes it to move in a straight path, then the mass of the particle is (Given charge of electron = 1.6 × 10-19 C)

A. 9.1 × 10-31 kg
B. 1.6 × 10-27 kg
C. 1.6 × 10-19 kg
D. 2.0 × 10-24 kg
Answer» E.
24.

A thin ring of 10 cm radius carries a uniformly distributed charge. The ring rotates at a constant angular speed of 40π rad/s about its axis, perpendicular to its plane. If the magnetic field at its centre is 3.8 × 10-9 T, then the charge carried by the ring is close to (μ0 =4π × 0-7 N/A2)

A. 2 × 10-6 C
B. 3 × 10-5 C
C. 4 × 10-5 C
D. 7 × 10-6 C
Answer» C. 4 × 10-5 C