If the magnetic field of the earth at any point on the magnetic equator is 0.4$\times$10^-4 T, then the value of the magnetic field at the magnetic pole of the earth is approximately

1. 0.4$\times$10^-4 T

2. 0.2$\times$10^-4 T

3. 0.8$\times$10^-4 T

4. 0.3$\times$10^-4 T

S.I. unit of intensity of magnetization is:

When the plane of a dip circle is along the magnetic meridian, the period of oscillations of dip needle is T₁. When the plane of dip circle is perpendicular to the magnetic meridian, the period of oscillations is T_2, then T₁/T₂ is (Angle of dip = 30$°$)

1. $\sqrt{2}$

2. 1

3. 2

4. $\frac{1}{\sqrt{2}}$

A ferromagnetic material is placed in an external magnetic field. The magnetic domains:

Magnetic permeability is maximum for

1. Diamagnetic substance

2. Paramagnetic substance

3. Ferromagnetic substance

4. Same for all three substances

The area enclosed by hysteresis loop is a measure of :

1. Permeability

2. Susceptibility

3. Retentivity

4. Energy loss per cycle

Line joining places of zero angle of dip on earth surface is called :

1. Isoclinic line

2. Aclinic line

3. Isogonic line

4. Agonic line

When a dip circle is kept at a place, the angle of dip obtained is 45$°$. When the dip circle is rotated about its vertical axis by 90$°$, the angle of dip obtained is 60$°$. The true dip at that place is :

1. cot^-1 $\left(\frac{2}{\sqrt{3}}\right)$

2. cot^-1$\left(\frac{4}{3}\right)$

3. ${\tan }^{-1}\left(\frac{2}{\sqrt{3}}\right)$

4. ${\tan }^{-1}\left(\frac{4}{3}\right)$

The magnetic moment of a bar magnet shown in figure(i) is M.

If a hole is drilled through the magnet as shown in figure(ii), then the new magnetic moment of the magnet will be :

1. Equal to M

2. Less than M

3. More than M

4. Zero