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#### Magnetism and Magnetic Effects of Electric Current Three Marks Questions

12th Standard EM

Reg.No. :
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Physics

Time : 01:00:00 Hrs
Total Marks : 30
10 x 3 = 30
1. The repulsive force between two magnetic poles in air is 9 x 10-3 N. If the two poles are equal in strength and are separated by a distance of 10 cm, calculate the pole strength of each pole.

2. A short bar magnet has a magnetic moment of 0.5 J T-1. Calculate magnitude and
direction of the magnetic field produced by the bar magnet which is kept at a distance
of 0.1 m from the center of the bar magnet along
(a) axial line of the bar magnet and
(b) normal bisector of the bar magnet.

3. Compute the intensity of magnetisation of the bar magnet whose mass, magnetic moment and density are 200 g, 2 A m2 and 8 g cm-3, respectively.

4. Using the relation $\overset { \rightarrow }{ B } =\mu _{ ° }(\overset { \rightarrow }{ H+ } \overset { \rightarrow }{ M } )$ show that ${ x }_{ m }={ \mu }_{ r }-{ 1 }$

5. The magnetic field shown in the figure is due to the current carrying wire. In which
direction does the current flow in the wire?.

6. Explain the principle and working of a moving coil galvanometer.

7. Discuss the conversion of galvanometer into an ammeter and also a voltmeter.

8. State that a current carrying loop behaves as a magnetic dipole. Hence write an expression for its magnetic dipole moment.

9. Obtain an expression for magnetic Lorentz force?

10. What is the value of magnetic field at point O due to current flowing in the wires?