A thin disc of radius R has charge Q uniformly distributed over its surface. The disc is rotated about one of its diametric axis with angular velocity w(omega). Then the magnetic moment of this arrangement is

1. QR²w/8
2. QR²w/4
3. QR²w/2
4. QR²w

Four long co-axial thin walled cylindrical conductor A, B, C and D have radii R. 2R 3R and 4R respectively. A and C carry current I and 31 respectively to plane of paper on the other hand, B and D carry and 41 respectively outward to plane of paper. Then 21

I need solution of these questions.............................Magnetic effect of current

A freely suspended iron rod does not point at N-S directions alwalys .why

 

 

What is magnetic entropy change? For my knowledge, I know entropy is randomness or disorder. So here that magnetic refers to the magnetic dipole moments?

Derive the relation between magnetic field intensity (H) and magnetization (M) for a magnetic material placed in a magnetizing field.