The time period of vibration of a bar-magnet in a vibration magnetometer is \(T\). If the magnet is cut into \(n\) identical parts such that the length of each part is equal to the length of the original magnet, then the time period of vibration of one part in the vibration magnetometer is:
1. \(\frac{T}{n}\)
2. \(nT\)
3. \(n^2T\)
4. \(T\)
Magnetic susceptibility of a substance at \(27^{\circ}~\mathrm{C}\) is \(-0.00025\). Its magnetic susceptibility at \(127^{\circ}~\mathrm{C}\) is:
1. \(-0.000125\)
2. \(-0.0005\)
3. \(-0.00025\)
4. \(-0.00001\)
Locus of all points having the same dip on the magnetic map of the earth is known as :
1. Isodynamic line
2. Isogonic line
3. Isothermal line
4. Isoclinic line
Magnetic induction at an axial point of a short magnet at a distance \(r\) from the centre of dipole is \(\vec B\). Its value at the equatorial point of the short magnet at the same distance from the centre of dipole is:
1. | \(-\vec B\) | 2. | \(\dfrac{\vec B}{2}\) |
3. | \(\vec B\) | 4. | \(\dfrac{-\vec B}{2}\) |
Consider a magnetic dipole kept in the east-west direction. Let P1, P2, Q1, Q2 be four points at the same distance from the dipole towards north, south, east and west of the dipole respectively. The directions of the magnetic field due to the dipole are the same only at:
1. P1 and Q1
2. P2 and Q1
3. P1 and Q2
4. Q1 and Q2
1. | \(9~\text{gauss}\) | 2. | \(4~\text{gauss}\) |
3. | \(36~\text{gauss}\) | 4. | \(4.5~\text{gauss}\) |
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. | \(M_A=2M_B\) |
Magnetic screening is:
1. Not possible
2. Possible using superconductors
3. Possible using the iron ring as cover
4. Both (2) & (3)
The apparent dip at a place is always greater than or equal to the value of true dip at that place. This is due to
1. An increase in the apparent value of BV
2. A decrease in the apparent value of BH
3. An increase in the apparent value of BH
4. Both (1) & (2)