SCIENCE CHAP ELECTRICITY & CIRCUITS TEXTUAL Q-ANS

Q5 Answer following questions in one word or one sentence. 

a. What forms the negative terminal of a dry cell? 

Answer:-The outer covering of a dry cell consists of zinc metal which acts as the  negative terminal for the dry cell. 

b. Give one example of a conductor. 

Answer:- copper 

c. What are insulators? 

Answer:- The materials that do not allow any current to pass through them are called  insulators.Eg:- Rubber,wood 

d. In which direction does a current flow in a circuit ? 

Answer:- Current flows in a circuit from positive terminal to negative terminal. 

e. What is the central part of an atom made up of protons and neutrons called? Answer:- Nucleus. 

Q6 Answer the following questions in short. 

a. What is an electric circuit? State its components. 

Answer :- The complete path through which an electric current flows is called an electric circuit. 

An electric circuit consists of following components:

b. State the difference between conductors and insulators. 

Answer:- 

c. State the difference between open circuit and closed circuit? 

Answer:-  

d. Name the type of electric cells, State one difference between them. Answer:- There are two types of electric cell  

1. Primary cell 

2. Secondary cell 

Difference between primary and secondary cell.

Primary Cell	Secondary Cell
Primary cells are batteries that cannot	Secondary cells are batteries that be

be recharged or reused	recharged or reused (known as lead acid accumulator)
Two types of dry cells are pencil cell and button cell	Car batteries are examples of secondary  cells
Can be used only once	Can be used more than once

e. What is an electric current? list some source of electric current. 

Answer:- An electric current is the flow of charge due to electrical energy. Sources of electric current 

1. Coal, petroleum 

2. Sun 

3. Wind 

4. Water 

5. Nuclear energy 

6. Oil  

7. Gas 

Q.7 Give reason: 

a. wires have a plastic and rubber covering. 

Answer:- Plastic and rubber are insulators which prevent current to flow from  wire and protects us from electric shocks. 

b. copper wire is used instead of wood in an electric circuit. 

Answer:- copper wire is a good conductor of electricity and wood is an insulator. That is why  copper wire is used in electric circuits. 

c. It is advisable not to put our hands inside a plug socket. 

Answer:- Our body is a good conductor of electric current and hence we can get an electric  shock if we put our finger inside a plug a socket. 

d. Tungsten is used as a filament in a bulb. 

Answer:- Tungsten is used as a filament in a bulb because the melting point of tungsten is very  high hence it does not melt even when the filament glows at a very high temperature.

Q.8 Answer the following questions in detail. 

a. list out the safety measures that should be followed while handling electrical appliances. Answer :- 

b. Explain the working of a bulb. 

Answer:- The incandescent light bulb turns electricity into light by sending the electric current through a thin wire called a  filament. Electrical filaments are made up mostly of tungsten metal. The resistance of the filament heats the bulb. Eventually the  filament gets so hot that it glows, producing light.

c. Explain the structure of primary cell. 

Answer :- 

a. In picture ‘V’ the bulb will glow…..because wires are connect with correct terminals. b.

Answer:- a. the bulb will glow in set up ‘A’. 

 Because the l in set up ’ A’  the switch is on. 

b. the ends of conducting wires are bare because those ends are required to be connected with battery  and only conducting surface can flow current through them.