A magnetic needle makes n oscillations per minute in a horizontal plane where the angle of dip is 45$°$. If the needle is made to oscillate in a vertical plane coinciding with the magnetic meridian, then the number of oscillations per minute will become/remains

1. n

2. $\sqrt{2}$n

3. (2)^1/4 n

4. n/2

Two similar nature magnetic poles of strength 16 A-m and 64 A-m are placed at a distance of 120 cm in air. At which point on the line joining the two poles, the force on another unit north pole will be zero?

1. 0.8 m from 64 A-m

2. 0.8 m from 16 A-m

3. 0.4 m from 64 A-m

4. 0.6 from 64 A-m

The magnetic moment of a short dipole is \(100\) A-m². The magnetic induction in vacuum at \(1\) m from the dipole on the axis of the dipole is:

A deflection magnetometer is placed in tanA position. The bar magnet is placed in :

1. East-West direction

2. North-south direction

3. North-east direction

4. South-West direction

Each of the two identical magnets, when suspended alone, makes 30 oscillations per minute at a place. The number of oscillations per minute, if they are fixed at right angles ( to form a cross) and allowed to oscillate in the same field will be approximate:

1. 25 oscillation/minute

2. 30 oscillation/minute

3. 60 oscillation/minute

4. 15 oscillation/minute

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. $\frac{1}{\sqrt{2}}$