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.
Select the incorrect statement regarding magnetic material.
1. | The magnetic dipole moment of each atom of para and ferromagnetic substance is zero and that of diamagnetic material is non-zero in the absence of external magnetizing force |
2. | When the diamagnetic substance is brought near the north or south pole of a bar magnet, it is repelled |
3. | Magnetic susceptibility of diamagnetic substances is temperature independent and that of para and ferromagnetic substances is temperature-dependent |
4. | All of these |
The relation amongst the three elements of Earth's magnetic field, namely horizontal component H, vertical component V and dip angle is: (=total magnetic field):
1. V=tan, H=
2. V=sin, H=cos
3. V=cos, H=sin
4. V=, H=tan
A current carrying coil is placed with its axis perpendicular to N-S direction. Let horizontal component of earth's magnetic field be and magnetic field inside the loop be H. If a magnet is suspended inside the loop, it makes angle with H. Then
1.
2.
3.
4.
A bar magnet has coercivity \(4\times 10^{3}~\text{Am}^{-1}\). It is desired to demagnetize it by inserting it inside a solenoid \(12~\text{cm}\) long and having \(60\) turns. The current that should be sent through the solenoid is:
1. \(2\) A
2. \(4\) A
3. \(6\) A
4. \(8\) A
A uniform magnetic field, parallel to the plane of the paper existed in space initially directed from left to right. When a bar of soft iron is placed in the field parallel to it, the lines of force passing through it will be represented by:
1. | 2. | ||
3. | 4. |
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. 0o
2. 30o
3. 45o
4. 90o
Assertion (A): | Magnetic flux linked with a closed surface is always zero. |
Reason (R): | Magnetic monopole does not exist. |
1. | Both (A) and (R) are True and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are True but (R) is not the correct explanation of (A). |
3. | (A) is True but (R) is False. |
4. | (A) is False but (R) is True. |
A frog can be levitated in a magnetic field produced by a current in a vertical solenoid placed below the frog. This is possible because the body of the frog behaves as:
1. | Paramagnetic | 2. | Diamagnetic |
3. | Ferromagnetic | 4. | None of these |
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