Electromagnetic Theory MCQs Question and Answer in Engineering Physics Page-7 section-1

61.
A left circularly polarized light beam of wavelength 600 nm is incident on a crystal of thickness d and propagates perpendicular to its optic axis. The ordinary and extraordinary refractive indices of the crystal are n_o = 1.54 and n_e and = 1.55 respectively. The emergent light will be right circularly polarized, if d is

A. 120 μm

B. 60 μm

C. 30 μm

D. 15 μm

Answer & Solution Discuss in Board Save for Later

62.
An atom with net magnetic moment $$\overrightarrow \mu $$ and net angular momentum $$\overrightarrow {\bf{L}} \left( {\overrightarrow \mu = \gamma \overrightarrow {\bf{L}} } \right)$$ is kept in a uniform magnetic induction $$\overrightarrow {\bf{B}} = {B_0}{\bf{\hat k}}.$$ The magnetic moment $$\overrightarrow \mu \left( { = {\mu _x}} \right)$$ is

A. $$\frac{{{d^2}{\mu _x}}}{{d{t^2}}} + \gamma {B_0}{\mu _x} = 0$$

B. $$\frac{{{d^2}{\mu _x}}}{{d{t^2}}} + \gamma {B_0}\frac{{d{\mu _x}}}{{dt}} + {\mu _x} = 0$$

C. $$\frac{{{d^2}{\mu _x}}}{{d{t^2}}} + {\gamma ^2}B_0^2{\mu _x} = 0$$

D. $$\frac{{{d^2}{\mu _x}}}{{d{t^2}}} + 2\gamma {B_0}{\mu _x} = 0$$

Answer & Solution Discuss in Board Save for Later

63.
When liquid oxygen is poured down close to a strong bar magnet, the oxygen stream is

A. repelled towards the lower field because it is diamagnetic

B. attracted towards the higher field because it is diamagnetic

C. repelled towards the lower field because it is paramagnetic

D. attracted towards the higher field because it is paramagnetic

Answer & Solution Discuss in Board Save for Later

64.
The work done in bringing a charge +q from infinity in free space, to a position at a distance d in front of a semiinfinite grounded metal surface is

A. $$ - \frac{{{q^2}}}{{4\pi {\varepsilon _0}\left( d \right)}}$$

B. $$ - \frac{{{q^2}}}{{4\pi {\varepsilon _0}\left( {2d} \right)}}$$

C. $$ - \frac{{{q^2}}}{{4\pi {\varepsilon _0}\left( {4d} \right)}}$$

D. $$ - \frac{{{q^2}}}{{4\pi {\varepsilon _0}\left( {6d} \right)}}$$

Answer & Solution Discuss in Board Save for Later

65.
A rod of length L with uniform charge density $$\lambda $$ per unit length is in the XY-plane and rotating about Z-axis passing through one of its edge with an angular velocity $$\overrightarrow \omega $$ as shown in the figure below. $$\left( {{\bf{\hat r}},\,\hat \phi ,\,{\bf{\hat z}}} \right)$$ refer to the unit vectors at Q, $$\overrightarrow {\bf{A}} $$ is the vector potential at a distance d from the origin O along Z-axis for d ≪ L and $$\overrightarrow {\bf{J}} $$ is the current density due to the motion of the rod. Which one of the following statements is correct?

A. $$\overrightarrow {\bf{J}} {\text{ along }}{\bf{\hat r}};\overrightarrow {\bf{A}} {\text{ along }}{\bf{\hat z}};\left| {\overrightarrow {\bf{A}} } \right| \propto \frac{1}{d}$$

B. $$\overrightarrow {\bf{J}} {\text{ along }}\hat \phi ;\overrightarrow {\bf{A}} {\text{ along }}\hat \phi ;\left| {\overrightarrow {\bf{A}} } \right| \propto \frac{1}{{{d^2}}}$$

C. $$\overrightarrow {\bf{J}} {\text{ along }}{\bf{\hat r}};\overrightarrow {\bf{A}} {\text{ along }}{\bf{\hat z}};\left| {\overrightarrow {\bf{A}} } \right| \propto \frac{1}{{{d^2}}}$$

D. $$\overrightarrow {\bf{J}} {\text{ along }}\hat \phi ;\overrightarrow {\bf{A}} {\text{ along }}\hat \phi ;\left| {\overrightarrow {\bf{A}} } \right| \propto \frac{1}{d}$$

Answer & Solution Discuss in Board Save for Later

66.
A dielectric sphere is placed in a uniform electric field directed along the positive Y-axis. Which one of the following represents the correct equipotential surfaces?

A. Electromagnetic Theory mcq question image

B. Electromagnetic Theory mcq question image

C. Electromagnetic Theory mcq question image

D. Electromagnetic Theory mcq question image

Answer & Solution Discuss in Board Save for Later

67.
Match the following:

List-I List-II

P. Rest mass 1. Timelike vector

Q. Charge 2. Lorentz invariant

R. Four-momentum 3. Tensor of rank 2

S. Electromagnetic field 4. Conserved and Lorentz invariant

A. P-2, Q-4, R-3, S-1

B. P-4, Q-2, R-1, S-3

C. P-2, Q-4, R-1, S-3

D. P-4, Q-2, R-3, S-1

Answer & Solution Discuss in Board Save for Later

68.
A copper wire of uniform cross-sectional area 1.0 × 0^-6 m² carries a current of 1 A. Assuming that each copper atom contributes one electron to the electron gas, the drift velocity of the free electrons (density of copper is 8.94 × 10³ kg/m³ and its atomic mass is 1.05 × 10^-25 kg) is

A. 7.4 × 10^-4 m/s

B. 74 × 10^-4 m/s

C. 74 × 10^-3 m/s

D. 7.4 × 10^-5 m/s

Answer & Solution Discuss in Board Save for Later

69.
The electromagnetic field due to a point charge must be described by Lienard Weichert potentials, when

A. the point charge is highly accelerated

B. the electric and magnetic fields are not perpendicular

C. the point charge is moving with velocity close to that of light

D. the calculation is done for the radiation zone i.e., far away from the charge

Answer & Solution Discuss in Board Save for Later

70.
Four point charges are placed in a plane at the following positions +Q at (1, 0), -Q at (-1, 0), + Q at (0, 1) and -Q at (0, -1).
At large distances the electrostatic potential due to this charge distribution will be dominated by the

A. monopole moment

B. dipole moment

C. quadrupole moment

D. octopole moment

Answer & Solution Discuss in Board Save for Later

List-I	List-II
P. Rest mass	1. Timelike vector
Q. Charge	2. Lorentz invariant
R. Four-momentum	3. Tensor of rank 2
S. Electromagnetic field	4. Conserved and Lorentz invariant

Electromagnetic Theory MCQs Question and Answer in Engineering Physics

Answer & Solution

Answer & Solution

63. When liquid oxygen is poured down close to a strong bar magnet, the oxygen stream is

Answer & Solution

64. The work done in bringing a charge +q from infinity in free space, to a position at a distance d in front of a semiinfinite grounded metal surface is

Answer & Solution

Answer & Solution

66. A dielectric sphere is placed in a uniform electric field directed along the positive Y-axis. Which one of the following represents the correct equipotential surfaces?

Answer & Solution

67. Match the following: List-I List-II P. Rest mass 1. Timelike vector Q. Charge 2. Lorentz invariant R. Four-momentum 3. Tensor of rank 2 S. Electromagnetic field 4. Conserved and Lorentz invariant

Answer & Solution

68. A copper wire of uniform cross-sectional area 1.0 × 0-6 m2 carries a current of 1 A. Assuming that each copper atom contributes one electron to the electron gas, the drift velocity of the free electrons (density of copper is 8.94 × 103 kg/m3 and its atomic mass is 1.05 × 10-25 kg) is

Answer & Solution

69. The electromagnetic field due to a point charge must be described by Lienard Weichert potentials, when

Answer & Solution

70. Four point charges are placed in a plane at the following positions +Q at (1, 0), -Q at (-1, 0), + Q at (0, 1) and -Q at (0, -1). At large distances the electrostatic potential due to this charge distribution will be dominated by the

Answer & Solution

63.
When liquid oxygen is poured down close to a strong bar magnet, the oxygen stream is

64.
The work done in bringing a charge +q from infinity in free space, to a position at a distance d in front of a semiinfinite grounded metal surface is

66.
A dielectric sphere is placed in a uniform electric field directed along the positive Y-axis. Which one of the following represents the correct equipotential surfaces?

67.
Match the following:

List-I List-II

P. Rest mass 1. Timelike vector

Q. Charge 2. Lorentz invariant

R. Four-momentum 3. Tensor of rank 2

S. Electromagnetic field 4. Conserved and Lorentz invariant

68.
A copper wire of uniform cross-sectional area 1.0 × 0^-6 m² carries a current of 1 A. Assuming that each copper atom contributes one electron to the electron gas, the drift velocity of the free electrons (density of copper is 8.94 × 10³ kg/m³ and its atomic mass is 1.05 × 10^-25 kg) is

69.
The electromagnetic field due to a point charge must be described by Lienard Weichert potentials, when

70.
Four point charges are placed in a plane at the following positions +Q at (1, 0), -Q at (-1, 0), + Q at (0, 1) and -Q at (0, -1).
At large distances the electrostatic potential due to this charge distribution will be dominated by the