Question

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

Answer 1

To solve this question, we will look upon the components in an electrical circuit. We will also study about the working of a key or a switch which is an essential part of an electrical circuit. Also we will see how a key is used to open and close a circuit.

Complete step by step answer:
To understand the concept of a key or a switch, we will study a simple electric circuit.

As we can see from the figure that a simple electric circuit comprises a power source (battery), conducting wires, a load resistance (light bulb), and an electrical switch.
As we all know that for a current to flow through a circuit, the circuit needs to be complete. But what if we want the current to flow at our command? That is when an electric switch comes into play. The switch is an electrical component by which we can open and close a circuit .i.e., start or stop the flow of current.

As we can see from the figure, when the switch is open, there is no flow of electric current in the circuit whereas when the switch is closed, there is a flow of electric current throughout the circuit.
Hence, the correct answer for our question is option (A) .

Note:
The main aim of an electric switch or a key is to stop or allow the flow of electric current in a circuit but there are more uses of electric switches and vary from circuit to circuit. For example, an electrical switch can also be used to divert the flow of electric current from one direction to another and so on.