Question

What is the function of a key (or switch) in an electric circuit?
A. To put or off current in a circuit
B. To put on or off voltage in a circuit
C. To put on or off power in the circuit
D. To put on or off resistance in a circuit

Answer 1

Hint: A switch is an electric component which is used to make or break a circuit. We know that electricity passes through a circuit only if the circuit is closed. The switch is generally connected in series to the load which it tries to regulate.

Complete step by step answer:
We know that a basic circuit contains a load, a source, a switch and some connecting wires. When the switch is plugged in, then there is electricity or current in the circuit. Then the circuit is called an open circuit.
The current flows from the source, passes through a load and back to the source again. This flow of current is called electricity.
When the switch is plugged out, the circuit is not complete and hence there is no current in the circuit. Then the circuit is called a closed circuit.
These switches are used to prevent electrical damages which occur when current flows through the load for long durations. We know that in series circuits, the current remains constant, thus if the flow of current in a series is disturbed then the current doesn’t flow through the load. Hence the switch is often connected in series with the load.
Thus we can say that the switch regulates the current in the circuit.

Hence the answer is A. to put or off current in a circuit.

Note:
A switch can be a toggle switch as used in the households or a pushbutton as in the keypads of the remotes. However there are other kinds of switch like rotating switch or reversing switch which are specific to the needs of the setup.