Electricity and circuits

1.Define electricity.

Ans Electricity is the flow of charges from positive terminal to the negative terminal.

2.What are the uses of electricity?

Ans 1. It is used to operate pumps to lift water from the well to tanks
2. It is used in the lighting of homes, streets, etc.
3. It is used in industries.
4. It is used in electric appliances.

3.Define an electric cell.

Ans Electric cell is a device that converts chemical energy to electrical energy. It has two terminals-

1. Positive terminal (metal cap is positive terminal)

2. Negative terminal (metal disk is negative terminal)

                                                 

The symbol of a cell is -    

  The symbol of a battery is -    

4. Define a battery.

Ans A battery is the combination of two or more cells.

5. Write the construction of an electric bulb.

Ans An electric bulb consist of a small glass cover fixed on metal case. Inside the glass cover there is a very thin wire fixed between two thick wires. The thin wire inside is called filament. Filament is usually made up of tungsten. It is the filament of the bulb which glows while electricity pass  through it. The two thick wires inside the glass bulb provides support to the filament and also makes the connection of the filament to the outer circuit. The lower end of one of the thick wires is connected to the metal tip at the bottom of the bulb. Whereas the lower end of the other thick wire is connected to the metals case. The metal tip of the bulb at the base and the metal case of the bulb are the two terminal of the bulb.

6. What is an electric circuit?
Ans The complete path of electricity between the two terminals of an electric cell is called and electric cell.

   

the symbol for bulb is

7. What are the different types of circuits?
Ans Electric circuits are of two types-1.Open circuit- when there is a breakage in the path of electricity is called an open circuit.2.Closed circuit- when there is no breakage in the path of electricity is called a closed circuit.

                      

8. What are the properties of a filament?
Ans The properties of a filament are-1. It has high resistance for electric current.2. It has high melting point.3. They don't get oxidized even at high temperature.

9. What is an electric switch ?
Ans Electric switch is an electric device which make or break a circuit. If it makes a circuit then it is switched on and if it breaks a circuit it is switched of.

10. Define-
a) Conductor- Substances that allow electricity to pass through them are called conductors of electricity. eg metal , our body, etc.
b) Insulator- Substances that don't allow electricity to pass through them are called insulators of electricity . eg pure water, diamond , wood , etc.

11. Why should an electrician use rubber gloves while preparing an electric switch at home?
Ans Our body is a good conductor of electricity and rubber is an insulator of electricity. During repairing work, if our body comes in contact to a wire carrying electricity , there will not be any accident as rubber doesn't allow the passage of current through it. Hence, electrician use rubber glows while repairing a switch.

12.The handles of tools like screw drivers, pliers, etc are made of plastic or rubber handles. Explain?
Ans Plastic and rubber are insulators of electricity. When these tools come in contact with current carrying wires. Due to plastic or rubber handle any accident don't occur.

13. Who invented electric bulb and electric cell?
Ans Thomas Alva Edison is the inventor of the electric bulb.
Alessandro Volta is the inventor of the electric cell.

14. What are the advantages of an electric cell.
Ans 1. Electric cell are light so they are portable 2. They produce very small amount of electricity so they are perfectly safe. So one can handle them without receiving an electric shock.3. They are not very costly.4. They don't contain any liquid chemicals that can be spilled.5. They supply a steady electric current.

        An electric cell



15. Why do bulbs have two terminals?
Ans Bulbs have two terminals to connect the filament with circuit so that current can easily pass through.

16. A fused bulb doesn't glow. Why?
Ans The circuit in a fused bulb is incomplete due to breaking of filament. thus, the fused bulb does no glow.

17. Rita wanted to glow a torch bulb using a cell she could not get connecting wires instead she used two stripes of aluminium foil. Will she succeed. How ?
Ans Aluminium foil is a good conductor of electricity so they can be used as connecting wires.

18.Write the preventive measures to avoid electric shock.
Ans 1.Replace the light bulb only when it is switched of and cool.2. Never touch electric switches or gadgets when your body is wet.3. Don't try to repair or install electrical wiring or appliances.4. Don't touch electric poses or transformers on the road.5. Don't touch a hanging wire on the road.6. Never fly kites near overhead power lines.7. Never join the electric wires with bare hands.

19. We remove the plastic coating from the ends of the electric wires while using in an electric circuit. Why ?
Ans It is because plastic is an insulator of electricity. We remove the plastic covering to connect the copper wires so that electric current can pass.

inside of a torch