12. ELECTRICITY AND CIRCUITS
Additional-Question with solution:
Que : What are conductors?
Ans : Materials that allow electric current to pass through them are called conductors.
Que : What are insulators?
Ans : Materials that do not allow electric current to pass through them are called insulators.
Que : Give three examples of conductors.
Ans : Iron, copper, Aluminium etc.
Que : Give three examples of insulators.
Ans : Wood , Plastic, and rubber etc.
Que : Write a source of electricity.
Ans : Electric cell is a source of electricity.
Que : How many terminals are there in electric cell? Name them.
Ans : There are two terminals in the electric cell, positive (+ Ve) and negative (-ve).
Que : How does electric cell produce electricity?
Ans : An electric cell produces electricity from the chemicals stored inside it.
Que : Name five device in which electric cells are used?
Ans : Electric cells are also used in alarm clocks, wristwatches, transistor radios, cameras and many other devices.
Que: What is called the filament of bulb?
Ans: The thin wire that gives off light is called the filament of the bulb.
Que: What happens when two terminals of cell is joined together?
Ans: The chemicals in the electric cell get used up very fast and the cell stops working.
Que: Why should an electrician use rubber gloves while repairing an electric switch at your home? Explain.
Ans: Rubber gloves are insulators which do not allow to pass electric current through themselves. So protect from electric shock an electrician uses rubber gloves.
Que: What is the purpose of using an electric switch?
Ans: The switches used in lighting of electric bulbs and other devices in homes work on the same principle although their designs are more complex.
Que: What is switch?
Ans: A switch is a simple device that either breaks the circuit or completes it.
Que: What is an electric circuit?
Ans: A close and curve path of electric current is called an electric circuit.
Que: Give regions not to glow bulb through a complete electric circuit.
Ans:
(1) The bulb may be fused.
(2) Battery may be discharged.
(3) Circuit may be made of insulator.
(4) Switch may be disconnected/off.
Que: Give a region for a bulb to fuse.
Ans: One reason for a bulb to fuse is a break in its filament.
Que: Name some electric gadgets in which switches are used?
Ans: Torch, Radio, Television, table fan.