Our country faces a shortage of electricity. So
wastage of electricity means you are depriving someone else of electricity. Your
electricity bill goes up. So, we must use electricity very carefully and only when it is needed. We
must use the electricity as long as we need it in our house hold activities.
Can you remember what you did last year to turn the current on or off?
This time, we shall use a switch to turn the
current on or off. You may have used different kinds of switches to turn your
household electric appliances on or off. Switches help us to start or stop the
appliances safely and easily.
Make your own switch
Let us make a switch of our
circuits. Take 10 cm long iron strip. Bend it twice as shown in figure. Now
drive a nail into the bend of the wooden block. Nail one end of the strip to
the other end of the wooden block so that its free end rests just above the
first nail without touching it. Your switch is ready.
Would you like to test your switch?
To do so, first set up the circuit as shown in the figure.
How would you use the switch to open
or close the circuit.
If the bulb in your circuit glows
when the metal strip of your switch is pressed on the nail and turns off when
it is not, then your switch is working. The switch you made is a simple one.
You may have seen many different types of switches on switchboards and
appliances at your home and school. The switches are designed according to
their usage, convenience and safety. But all of them work on the same
principle. Switch is a mechanical component that consists of two or more
terminals that are internally connected to a metal strip. Commonly used
switches are listed below: