A. Choose the correct answer.

1. Which of these is not a source of electric power?

(a) Dry cell (b) Diesel generator (c) Electric torch (d) Solar cell

c. Electric torch

• The filament of the bulb glows because

a. its temperature drops

b. the gas present in the bulb conducts electric current

c. it does not allow an electric current to pass through

d. the electric current passing through it heats it up

Answer .d. The electric current passing through it heats it up.

• An electric switch can

a. only break an electric circuit

   b. only close an electric circuit

  c. both open and close an electric circuit

  d. give out light if an electric current passes through it

   Answer. c. Both open and close an electric circuit.

• Which of the following materials is not an insulator?

a. Rubber

    b. Wood

    c. Graphite

    d. Distilled water

    Answer. c. Graphite

• Which of these materials is not a conductor?

a. Dry air

    b. Copper

   c. Graphite

    d. Silver

Answer.a. Dry air

B. Fill in the blanks with the correct words.

1. We can find a filament in a ________ (dry cell/electric bulb).

We can find a filament in an electric bulb.

An electric cell is a source of electric current.

1. A clock cell is an example of a dry cell.
2. Electric cells that can be recharged are called secondary cells.
3. Copper and silver are examples of good conductors.

C. Explain the following terms.

1. Dry cell: A dry cell is a small, portable device that generates electricity using chemical reactions. It has two terminals – a positive and a negative – that provide electric current when connected to a circuit.
2. Filament: The filament is a thin wire inside an electric bulb that glows when electricity passes through it. It gets heated due to resistance and produces light.
3. Electric circuit: An electric circuit is a closed path through which electricity flows. It includes a power source (like a battery), wires, and electrical components such as bulbs or switches.
4. Electric switch: An electric switch is a device that opens or closes a circuit, allowing or stopping the flow of electricity. When switched on, the circuit is complete, and when switched off, the circuit is broken.
5. Conductors: Conductors are materials that allow electricity to pass through them easily. Examples include copper and silver.
6. Insulators: Insulators are materials that do not allow electricity to pass through them. Examples include rubber and plastic.

D. Answer the following.

1. Name three sources of electric current.
   1. Dry cell
   1. Solar cell
   1. Car battery
2. Give a brief description of a dry cell.
   A dry cell is a small, portable source of electricity that generates current through a chemical reaction. It has a positive terminal (carbon rod) and a negative terminal (zinc case). It is commonly used in torches, clocks, and remote controls.
3. What is an electric circuit? Draw a simple electric circuit with a cell and a bulb.

An electric circuit is a closed loop that allows electric current to flow. It consists of a power source, connecting wires, and a load (such as a bulb).

(Simple circuit diagram: A battery connected to a bulb using wires.)

• What are the conditions necessary to set up an electric circuit?
  • A power source like a battery or cell.
  • Conducting wires to carry the current.
  • A load (e.g., a bulb) to use the electricity.
  • A closed path (the circuit must be complete).
• Draw a diagram and explain how an electric torch works.

• An electric torch has a battery as its power source.
  • When the switch is turned on, it completes the circuit.
  • Electricity flows to the bulb, making the filament glow.
  • The reflector around the bulb directs the light forward.
• What are conductors and insulators? Give two examples of each.
  • Conductors: Materials that allow electricity to flow through them. Examples: Copper, Silver.
  • Insulators: Materials that do not allow electricity to flow. Examples: Rubber, Wood.
• Write down one use for each of the conductors and insulators.
  • Conductors: Copper is used in electric wires.
  • Insulators: Rubber is used to cover electrical wires for safety.
• Write a few lines about electrical safety.
  • Never touch electrical appliances with wet hands.
  • Do not insert metal objects into electrical sockets.
  • Always turn off electrical devices when not in use.
  • Use proper insulation to prevent electric shocks.