Questions Answers

Evaluation

I. Choose the appropriate answer

1. The device which converts chemical energy into electrical energy is

a. fan

b. solar cell

c. cell

d. television

Answer: c. cell

2. Electricity is produced in

a. transformer

b. power station

c. electric wire

d. television

Answer: b. power station

3. Choose the symbol for battery

Answer: c

4. In which among the following circuits does the bulb glow?

Answer: d

5. ______ is a good conductor

a. silver

b. wood

c. rubber

d. plastic

Answer: a. silver

II. Fill in the blanks

1. Conductor are the materials which allow electric current to pass through them.

2. Flow of electricity through a closed circuit is current.

3. Switch is the device used to close or open an electric circuit.

4. The long perpendicular line in the electrical symbol represents its positive terminal.

5. The combination of two or more cells is called a battery.

III. True or False. If False, give the correct statement

1. In a parallel circuit, the electricity has more than one path. [True]

2. To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. [False]

To make a battery of two cells, the negative terminal of one cell is connected to the positive terminal of the other cell.

3. The switch is used to close or open an electric circuit. [True]

4. Pure water is a good conductor of electricity. [False]

Pure water is a bad conductor of electricity

5. Secondary cell can be used only once. [False]

Secondary cells can be recharged and used again and again.

IV Match the following

V. Arrange in sequence

Answer: A CELL IS A DEVICE THAT CONVERTS CHEMICAL ENERGY INTO ELECTRICAL ENERGY

VI. Give very short answer

1. In the given circuit diagram, which of the given switch(s) should be closed. So that only the bulb A glows.

Answer: K₁ & K₂

2. Assertion (A) : It is very easy for our body to receive electric shock.

Reason (R) : Human body is a good conductor of electricity.

a. Both A and R are correct and R is the correct explanation for A.

b. A is correct, but R is not the correct explanation for A.

c. A is wrong but R is correct.

d. Both A and R are correct and R is not the correct explanation for A.

Answer: a. Both A and R are correct and R is the correct explanation for A.

3. Can you produce electricity from lemon?

Yes, lemon juice should be used as electrolyte. A copper plate and a zinc plate should be made electrodes. By connecting them with a wire we get electricity passing from +ve copper to -ve zinc.

4. Identify the conductor from the following figures.

5. What type of circuit is there in a torch light?

Series Circuit

6. Circle the odd one out. Give reason for your choice.

Switch, Bulb, Battery, Generator.

Switch, Bulb, Battery, (Generator).

Switch, bulb and battery are parts of series circuit Generator does not find a place in it.

VII. Give short answer

1. Draw the circuit diagram for series connection.

L - Lamp

C - Cell

K - Key 

2. Can the cell used in the clock gives us an electric shock? Justify your answer.

The cell used in the clock does not give us an electric shock. This is because of low voltage current in the cell. So it does not give us shock.

3. Silver is a good conductor but it is not preferred for making electric wires. Why?

Silver is a good conductor but it is very expensive. So it is not preferred for making electric wires. We use aluminum or copper wires which are good conductors and are very cheap when compared to silver.

VIII. Answer in detail

1. What is the source of electricity? Explain the various power stations in India?

Any device from which electricity is produced is called the source of electricity.

• Thermal Power Stations are in Neyveli and Ennore.

• Hydel Power Stations are in Mettur and Papanasam.

• Atomic Power Stations are in Kalpakkam and Koodankulam.

• Windmills are in plenty in Aralvaimozhi and Kayatharu.

The following are some of the power stations in India.

1) Kishanganga Hydroelectric Plant

2) Solal Hydroelectric Power Station

3) Tarapur Atomic Power Station

4) Nabinagar Thermal Power Project

5) Kaiga Atomic Power Station

6) Mundra Thermal Power Station, Gujarat

7) Rajasthan Atomic Power Station

8) Barauni Thermal Power Station

9) Gujarat Solar Park

10) Vindhyachal Thermal Power Station, Madhya Pradesh.  

2. Tabulate the different components of an electric circuit and their respective symbols.

An electric circuit is the continuous or unbroken closed path along which electric current flows from the positive terminal to the negative terminal of the battery. A circuit generally has:

a) A cell or a battery - a source of electric current

b) Connecting wires - for carrying current

c) A bulb - a device that consumes the electricity

d) A key or a switch - this may be connected anywhere along the circuit to stop or allow the flow of current.

3. Write short notes on conductors and insulators.

The materials which allow electric charges to pass through them are called conductors.

Examples: Copper, iron, aluminum, impure water, earth etc.

Insulators (Non-Conductors) The materials which do not allow electric charges to pass through them are called insulators or non- conductors. Examples: plastic, glass, wood, rubber, china clay, ebonite etc.,

IX. Question based on Higher Order Thinking Skills

1. Rahul wants to make an electric circuit. He has a bulb, two wires, a safety pin and a piece of copper. He does not have any electric cell or battery. Suddenly he gets some idea. He uses a lemon instead of a battery and makes a circuit. Will the bulb glow?

Yes, the bulb will glow. The safety pin and the piece of copper should be inserted into the lemon as electrodes. Copper is the +ve terminal and the pin is the -ve terminal. They should be connected to a bulb with two wires. The lemon juice acts as electrolyte and current passes from copper to the pin. As a result the bulb glows.

X. Search ten words in the given word grid and classify them as conductors and insulators