Explain working of an electromagnet.

(a) Name one device which works on the magnetic effect of current. (b) Name one device which works on the phenomenon of electromagnetic induction. (c) Which device converts electric energy into mechanical energy? (d) Describe the principle of working of an electric motor. (e) Explain the principle of working of an electric generator.

Explain the working of a transistor as a switch.

Explain the working of an astronomical telescope using refraction of light.

Explain the working of LED.