Free short Essay on Telephone – A Scientific Device. The primitive phones presented a slack and time-consuming service in the past. Booking a call in the morning and materializing it by night, was the usual practice.
Earthing is a safety device used to prevent a shock due to leakages arising from weak insulation, breaking of the element or otherwise.
A switch is a device which can close and open an electric circuit. A switch should always be connected on the live-wire side, so that when the switch is off, the element or bulb is neutral.