If a magnet is suspended at angle to the magnetic meridian, the dip needle makes an angle of with the horizontal. The value of real dip angle at the place is
1.
2.
3.
4.
Time period for a magnet is T. If it is divided in four equal parts along its axis and perpendicular to its axis as shown then time period for each part will be
1. 4T
2. T/4
3. T/2
4. T
Two equal bar magnets are kept as shown in the figure. The direction of the resultant magnetic field, indicated by arrowhead at the point \(P\) is: (approximately)
1. | 2. | ||
3. | 4. |
The relative permeability of a ferromagnetic substance varies with temperature (T) according to the curve:
1. A
2. B
3. C
4. D
The magnetic field due to a short magnet at a point on its axis at a distance X cm from the middle point of the magnet is 200 Gauss. The magnetic field at a point on the neutral axis at a distance of X cm from the middle of the magnet is:
1. 100 Gauss
2. 400 Gauss
3. 50 Gauss
4. 200 Gauss
For substances hysteresis (B - H) curves are given as shown in figure. For making temporary magnet which of the following is best?
1. | 2. | ||
3. | 4. |
A long solenoid has 1500 turns per metre and an iron core of = 1100 is kept inside it. 2A current flows in the coil of the solenoid. If the core is heated beyond curie temperature, then:
1. | The H and B fields in the solenoid reduce to zero. |
2. | The H and B fields in the solenoid remain unchanged. |
3. | The H field in the solenoid is nearly unchanged but B field decreases significantly. |
4. | The B field in the solenoid is nearly unchanged but the H field decreases significantly. |
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. |
The magnetic moment of a magnet \((10 ~\text{cm}\times 4~\text{cm}\times1~\text{cm})\) is \(4 ~\text{Am}^2\). Its intensity of magnetisation is:
1. \(10^{3}\) A/m
2. \(10^{2}\) A/m
3. \(10^{5}\) A/m
4. \(10^{4}\) A/m
If a magnetic dipole of dipole moment is rotated through an angle with respect to the direction of the magnetic field B, then work done is :
1. Bsin
2. B(1-sin)
3. Bcos
4. B(1-cos)
The magnetic dip at two perpendicular positions of a dip circle is 45 and 30. The true dip at that place is :
The magnetic susceptibility \(\chi\) of a diamagnetic material depends on absolute temperature \(T\) as:
1. \(\chi \propto T\)
2. \(\chi \propto \frac{1}{T}\)
3. \(\chi \propto T^0\)
4. \(\chi \propto \frac{1}{\sqrt{T}}\)
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 |
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. | \(M_A=2M_B\) |
A small bar magnet is placed with its north pole facing the magnetic north pole. The neutral points are located at a distance r from its centre. If the magnet is rotated by 180o, the neutral point shall be obtained at a distance of:
1. \(2r\)
2. \(\sqrt{2}r\)
3. \(2^{\frac{1}{3}}r\)
4. \(\frac{r}{2\sqrt{2}}\)