Question

What is a relay?

(a) A device that resists the flow of Current

(b) A device that resists the flow of direction in two ways

(c) Device that allows small electrical current to control large electrical current

(d) A device that allows the operator to control the current flow in the required direction

The question was posed to me in an interview.

My question comes from Engine Starting Methods in division Diesel Engine Plant of Energy Engineering

Answer 1

The correct choice is (c) Device that allows small electrical current to control large electrical current

Easiest explanation: A relay is a device that allows a small amount of electrical current to control a large amount of current. An automobile starter uses a large amount of current to start an engine. If we allow much current to go through the ignition switch, we would need a very large switch.