Electricity and Circuits

 A. Objective Type Questions:

1. b

2. c

3. c

4. d

5. a

6. c

7. b

8. b

B. Fill in the blanks:

1. two, direct

2. series

3. fused

4. complete

5. electrical circuit

C. True or False

1. F

2. F

3. T

4. T

5. F

II. Short – Answer Questions:

Q. 1: How are the cells connected in a torch? What is such combination called?

Ans. 1: In torch, the cells are connected in such a way that the positive terminal of one cell is in connect with the negative terminal of the other cell. This combination of cells is called a battery of cells.

Q. 2: What is meant by a closed electrical circuit?

Ans. 2: The circuit in which electrical current flows from one terminal of a cell or battery to the other is called a closed circuit.

Q. 3: Why does a fused bulb not glow?

Ans. 3: A bulb is said to be fused, when its filament is broken. The broken filament cannot complete the circuit. As result, current cannot flow through the filament and the fused bulb does not glow.

Q. 4: Differentiate between a conductor and an insulator.

Ans.4:

	Conductor	Insulator
1	Those substances through which electricity can flow are called conductors.	Those substances through electricity cannot flow are called insulators.
2	These substances have number of free electrons to allow the flow of electricity	These substances do not have number of free electrons to allow the flow of electricity.
3	Examples: copper, aluminum etc.	Example: paper, wood etc.

 Q. 5: Can electric wires be covered with aluminum foil instead of rubber or PVC? Give reason in support of your answer. 

Ans. 5: No, it can't be covered with aluminum foil as aluminum is a conductor of electricity and we may get electric shock whereas plastic is a bad conductor of electricity, so it is used to cover wires.

III . Long Answer Type Questions:

Q. 1: Name the source of electricity in a torch. Draw a diagram showing the inner view of that source.  

Ans. 1: The dry cell also called battery cell or electric cell.

Note: Draw the diagram of “the inner view of a dry cell" from book.

Q. 2: Why does the bulb not glow in the given circuit? Give reason. What arrangement will make the bulb glow?

Ans. 2: The bulb does not glow as in the circuit switch is OFF. The bulb will glow when switch will be ON.

Q. 3: What is meant by series combination of cells? Illustrate this by giving a suitable diagram.

Ans. 3: In series combination, the positive terminal of the first cell is connected to the negative terminal of the second cell and positive terminal of the second cell is connected to the negative terminal of the third cell and so on.

Q. 4: How does electricity flow in an electric circuit? What is meant by an open circuit?

Ans. 4:  Electricity only flows when a circuit is complete - when there are no gaps in it. In a complete circuit, the electrons flow from the negative terminal of the power source, through the connecting wires and components, such as bulbs, and back to the positive terminal. 

Open Circuit: An open circuit means that the circuit is not complete. It is broken somewhere. It can be a gap remaining in the connection or by the intervention of an electric component, such as a switch. No current flows in an open circuit.

Q. 5: What is the role of electric switch in a circuit? What kind of material is used for making the body / casing of electrical switches?

Ans. 5: A switch is a device which can be used to make or break a circuit. If that circuit carries a voltage which would be dangerous to people or animals, then the handle of the switch must be made of a good insulator, and the rest of the switch must be well shielded to stop anyone - or anything else - from touching any live wires.

Q. 6: Describe an experiment to find out whether the given material is a conductor or an insulator. 
Ans. If we create a simple circuit with the help of given material and connecting wires and then connect it with a battery and switch. Then turn ON the switch: 

• If the bulb is glowing then that material is the conductor of electricity.

• If the bulb does not glow that material is an insulator.

IV. HOTS:

1. Is human body a conductor or nonconductor of electricity?

Ans: The human body is a conductor of electricity. This is because the body contains a significant amount of water and electrolytes (salts and minerals) that allow electric current to flow through it.

2. An electrician while handling any electrical appliance/circuit wears rubber shoes and/or rubber gloves. Why?

Ans: An electrician wears rubber shoes and gloves because rubber is an insulator, preventing the flow of electricity through the body, thus reducing the risk of electrical shock or electrocution while working.

3. Why solar cell panels used in artificial satellites / space stations?

Ans: Solar cell panels are used in artificial satellites and space stations because they efficiently convert sunlight into electricity, providing a reliable, renewable energy source in space. Since space lacks other power options, solar panels are ideal for continuous power generation, essential for operating systems and equipment in orbit.