In a coil, the current changes from -2 A to +2 A in 0.2 s and induces an emf of 0.1 V. The self-inductance of the coil is:

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?