In a magnetic material, always there exist magnetic dipoles as well as monopoles. State True/False.

Two magnetic dipoles of magnitude m each are placed in a plane as shown below. The energy of interaction is given by
Electromagnetic Theory mcq question image

Electromagnetic Theory mcq question image

A

zero

B

$$\frac{{{\mu _0}}}{{4\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

C

$$\frac{{3{\mu _0}}}{{2\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

D

$$ - \frac{{3{\mu _0}}}{{8\pi }} \cdot \frac{{{m^2}}}{{{d^3}}}$$

In a static magnetic field only magnetic dipoles exist. State True/False.

A

True

B

False

Statement A: The pole of a magnet cannot be separated by breaking the magnet into two pieces. Statement B: Magnetic monopoles do not exist.

A

Statement A is correct

B

Statement B is correct

C

Both A and B are correct

D

Both A and B are incorrect

Consider the following statements regarding magnetic materials: 1. A diamagnetic material has no permanent dipole 2. Paramagnetic material has anti parallel orientation of equal moments with neighbouring dipoles 3. Ferrimagentic material has anti parallel orientation of unequal moments between neighbouring diploes Which of these statements are correct?

A

1 and 2

B

3 and 4

C

2 and 4

D

1 and 3

Consider the following statements regarding hysteresis loops of hard and soft magnetic materials: 1. Hysteresis loss of hard magnetic material will be less than that of soft material 2. Coercivity of hard material will be greater than that of soft material 3. Retentivity of the two materials will always be equal Which of these statements are correct?

A

1, 2 and 3

B

2 only

C

3 only

D

1 and 3 only

Given below are six sentences. A and F are the first and the last sentences. The rest of the sentences namely B, C, D and E are jumbled. Select the option that gives their correct order. A. The well was highly useful to the people who lived in the surrounding huts. B. The well was dangerous: but it had been there for so long that no one worried about it. C. Consequently, the mouth of the well had gradually widened as the soil and rocks on the side fell in. D. There had never been any money for a wall around the well. E. They had dug it two years before because the only water tap in the colony was not enough for the slum’s growing population. F. Apart from a chicken that had fallen in and had been rescued, the well seemed harmless.

A

ADBECF

B

AEBDCF

C

ADBCEF

D

AEDCBF

Renu's grandmother shows her a dried-up well and tells her that 15-20 years ago there was water in the well, but now it has completely dried up. What could be the reason(s) for drying up of water in the well ? A. The soil around the trees, well and nearby area is now covered with cement. B. A lot of boring pumps have come up in the nearby area. C. Nobody uses the well as there are taps in everybody's house now.

A

Only C

B

Only A

C

Only B

D

A and B

Which of the following explains non-existence of magnetic monopoles?

A

Lenz's law

B

Gauss law of magnetism

C

Universal law of gravitation

D

Henry's law

The reason for non existence of magnetic monopoles is

A

The magnetic field cannot be split

B

Due to permeability

C

Due to magnetization

D

Due to magnetostriction

Which one of the following Maxwell's equations implies the absence of magnetic monopoles?

A

$$\nabla .\overrightarrow {\bf{E}} = \frac{\pi }{{{\varepsilon _0}}}$$

B

$$\nabla .\overrightarrow {\bf{B}} = 0$$

C

$$\nabla \times \overrightarrow {\bf{E}} = - \frac{{\partial \overrightarrow {\bf{B}} }}{{\partial t}}$$

D

$$\nabla \times \overrightarrow {\bf{B}} = \left( {1/{c^2}} \right)\frac{{\partial \overrightarrow {\bf{B}} }}{{\partial t}} + {\mu _0}{\bf{\hat j}}$$

In a magnetic material, always there exist magnetic dipoles as well as monopoles. State True/False.

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