The material which is used to make permanent magnet has:
1. | High retentivity, low coercivity |
2. | Low retentivity, low coercivity |
3. | Low retentivity, high coercivity |
4. | High retentivity, high coercivity |
Which of the following is not dimensionless?
(where symbols stand for their usual meanings in magnetism)
1.
2.
3.
4.
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:
1. \(2\times10^{-5}~\text{T}\)
2. \(10^{-5}~\text{T}\)
3. \(2~\mu\text{T}\)
4. \(1~\mu\text{T}\)
The magnetic moment of a magnet \((10 ~cm\times 4~cm\times1~cm)\) is \(4 ~Am^2\). Its intensity of magnetisation is:
1. 103 A/m
2. 102 A/m
3. 105 A/m
4. 104 A/m
S.I. unit of intensity of magnetization is:
1. | Ampere-metre | 2. | Ampere-metre2 |
3. | Ampere/metre | 4. | Ampere/metre2 |
A ferromagnetic material is placed in an external magnetic field. The magnetic domains:
1. | must increase in size. |
2. | must decrease in size. |
3. | may increase or decrease in size. |
4. | disappear. |
Due to a small magnet, the intensity at a distance \(x\) in the end-on position is \(9~\text{gauss}\). What will be the intensity at a distance \(\frac{x}{2}\) on equatorial position?
1. \(9~\text{gauss}\)
2. \(4~\text{gauss}\)
3. \(36~\text{gauss}\)
4. \(4.5~\text{gauss}\)
The magnetic moment of a bar magnet of length \(L\) and area of cross-section \(A\) is \(M\). If the magnet is cut into four identical parts each of length \(L\) and area of cross-section \(\frac{A}{4}\), then magnetic moment of each part is:
1. | \(\frac{M}{4}\) | 2. | \(\frac{M}{2}\) |
3. | \(M\) | 4. | \(4M\) |
The possible value of magnetic susceptibility of a diamagnetic material can be:
1. -2.45
2. 0.75
3. -0.5
4. 1.67
The bar magnet \(A\) of magnetic moment \(M_A\) is found to oscillate at a frequency twice that of magnet \(B\) of magnetic moment \(M_B\) and the same moment of inertia when placed in a vibration magnetometer. We may say that:
1. \(M_B=8M_A\)
2. \(M_A= 4M_B\)
3. \(M_A=8M_B\)
4. \(M_A=2M_B\)