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 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 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 |
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 closely wound solenoid of \(2000\) turns and area of cross-section \(1.5\times10^{-4}\) m2 carries a current of \(2.0\) A. It is suspended through its center and perpendicular to its length, allowing it to turn in a horizontal plane in a uniform magnetic field \(5\times 10^{-2}\) tesla making an angle of \(30^{\circ}\) with the axis of the solenoid. The torque on the solenoid will be:
1. \(3\times 10^{-3}\) Nm
2. \(1.5\times 10^{-3}\) Nm
3. \(1.5\times 10^{-2}\) Nm
4. \(3\times 10^{-2}\) Nm
The current of 30 A is flowing in a vertical straight wire. If the horizontal component of the earth's magnetic field is 2 x 10-5 Tesla, then the position of the null point will be:
1. 0.9 m
2. 0.3 mm
3. 0.3 cm
4. 0.3 m
A magnet is parallel to a uniform magnetic field. If it is rotated by \(60^{\circ}\), the work done is \(0.8\) J. How much work is done in moving it \(30^{\circ}\) further?
1. \(0.8\times 10^{7}~\text{ergs}\)
2. \(0.4~\text{J}\)
3. \(8~\text{J}\)
4. \(0.8~\text{ergs}\)