Two conducting circular loops of radii R1 and R2 are placed in the same plane with their centres coinciding. If R1 >> R2, the mutual inductance M between them will be directly proportional to:

A step-down transformer connected to an AC mains supply of 220 V operates an 11 V, 44 W lamp. Ignoring power losses, what is the current in the primary circuit?

A transformer has 200 turns in its primary winding and 1000 turns in its secondary winding. What type of transformer is this?