Question

A small circular thing that you push to activate a machine is…..?

Answer 1

Hint: In order to solve this question we need to understand how current flows. So when a body is subjected to potential difference it creates an electric field to flow. Electric field produced would flow in the direction of decreasing potential and due to this flow it creates an external force on electrons in opposite direction so a current flows in the same direction as of electric field.

Complete answer:
Now when this current flows various machines start working and converting one form of energy into another like an electric motor converting mechanical energy to electric energy.So to control a machine a basic requirement is to control the flow of current inside the machine means we need a checkpoint so as to keep a watch over current.We use switches on the electrical circuits which can control the flow of current inside the machine.

Switch is an electrical device having a contact wire inside it so when the switch is on its wire connects the circuit and current flows but if we switch off then the connection made is broken and hence current flows stops which in turn stops the machine.

Note: It should be remembered that a switch can be physical or virtual like we can use a transistor as a switch in digital circuits where two bits denote switch off and on.Transistor works in three different regions: active, cutoff and saturation. Saturation is considered as switch on and cutoff is considered as switch off.