Each atom of an iron bar (5 cm × 1 cm × 1 cm) has a magnetic moment . Knowing that the density of iron is atomic weight is 56 and Avogadro's number is the magnetic moment of the bar in the state of magnetic saturation will be:
1. 4.75 Am2
2. 5.74 Am2
3. 7.54 Am2
4. 75.4 Am2
A dip needle vibrates in the vertical plane perpendicular to the magnetic meridian. The time period of vibration is found to be 2 seconds. 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
A dip needle lies initially in the magnetic meridian when it shows an angle of dip at a place. The dip circle is rotated through an angle x in the horizontal plane and then it shows an angle of dip . Then is
1. 1/cos x
2. 1/sin x
3. 1/tan x
4. cos x
A bar magnet has coercivity . It is desired to demagnetize it by inserting it inside a solenoid 12 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
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. |
The variation of magnetic susceptibility with temperature for a diamagnetic substance is best represented by
1.
2.
3.
4.
The variation of magnetic susceptibility with absolute temperature T for a ferromagnetic material is
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
Which curve may best represent the current deflection in a tangent galvanometer ?
1. A
2. B
3. C
4. D
Some equipotential surfaces of the magnetic scalar potential are shown in the figure. The magnetic field at a point in the region is: (X-axis read in cm)
1.
2.
3.
4. None of these