Why current is not possible, without the source of e.m.f?

Whenever changing current is passed through a conductor, an e.m.f. is induced, that is.

A 25 (mu)F capacitor, a0.1 H inductor and a 25 Omega resistorare connected in series with an ac source of emf E=310 sin 314 t. Find the current in the circuit.

When current in a coil changes with time, how is the back e.m.f. induced in the coil related to it?

A conductor of length L is connected across a dc source of e.m.f E. If the conductor is replaced by another of the same materials and area of cross-section but of length 5 L, by what factor will the drift velocity change?

A toaster produces more heat than a light bulb, when connected in parallel across a source of e.m.f. Which has greater resistace and why?

Derive a relation for the impedance of LCR circuit. What is the relationship between the current and e.m.f. in LCR circuit.