If the apparent value of dip at a place in two perpendicular vertical planes are respectively 30$°$ and 45$°$, then the true angle of dip at that place is

1. cot^-1(2)

2. tan^-1(2)

3. cot^-1($\sqrt{3}$)

4. cot^-1($\sqrt{5}$)

The magnetic moment of a magnet \((10 ~\text{cm}\times 4~\text{cm}\times1~\text{cm})\) is \(4 ~\text{Am}^2\). Its intensity of magnetisation is:
1. \(10^{3}~\text{A/m}\)
2. \(10^{2}~\text{A/m}\)
3. \(10^{5}~\text{A/m}\)
4. \(10^{4}~\text{A/m}\)

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