The vertical component of the earth's magnetic field is zero at:

1. The magnetic poles.

2. The magnetic equator.

3. The geographic poles.

4. The geographic equator.

The relation amongst the three elements of Earth's magnetic field, namely horizontal component H, vertical component V and dip angle$$ $\delta$ is: ($B_E$=total magnetic field):

1. V=$B_E$tan$\delta$, H=$B_E$

2. V=$B_E$sin$\delta$, H=$B_E$cos$\delta$

3. V=$B_E$cos$\delta$, H=$B_E$sin $\delta$

4. V=$B_E$, H=$B_E$tan$\delta$ 

A current carrying coil is placed with its axis perpendicular to N-S direction. Let horizontal component of earth's magnetic field be ${\mathrm{H}}_0$ and magnetic field inside the loop be H. If a magnet is suspended inside the loop, it makes angle $\mathrm{\theta }$ with H. Then $\mathrm{\theta \; equal\; to:}$

1. ${\tan }^{-1}\left(\frac{H_0}{H}\right)$

2. ${\tan }^{-1}\left(\frac{H}{H_{\mathit{0}}}\right)$

3. $\cos e{c}^{-1}\left(\frac{H}{H_{\mathit{0}}}\right)$

4. $co{t}^{-1}\left(\frac{H_0}{H}\right)$

A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 seconds. If the same needle is then allowed to vibrate in the horizontal plane and the time period is again found to be 2 seconds, then the angle of dip is:

1. 0^o

2. 30^o

3. 45^o

4. 90^o

A dip needle in a plane perpendicular to magnetic meridian will remain:
1. Vertical
2. Horizontal
3. In any direction
4. At an angle of dip to the horizontal

The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is:

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

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

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

4. ${\sin }^{-1}\left(\frac{3}{5}\right)$

If H is the horizontal component of the earth's magnetic field and 'V' is the vertical component of the earth's magnetic field, then at the magnetic equator:

1. V and H are equal.

2. values of V and H are zero.

3. value of H is zero only.

4. value of V is zero only.

An electric cable is carrying current from north to south. The position of the null point from the cable is:

1. Vertically upward

2. Vertically downward

3. Eastward

4. Nowhere

Which of the following graphs represents the correct variation of the intensity of magnetisation (I) with the intensity of the magnetising field (H) in a ferromagnetic substance?

1.		2.
3.		4.

The magnetic susceptibility χ of a ferromagnetic material varies with temperature, as:

1.		2.
3.		4.