Q.1.Draw the following electrical components: connecting wires, bulb, cell, switch in ‘ON’ and ‘OFF’ position and battery.
Q.2. Draw a circuit diagram for the following:
The circuit diagram for the above diagram is:
Q.3. The batteries shown below must be connected with wires. Using lines show how you will link the four batteries.
It should be connected in such a way that negative of the battery is linked to the positive terminal of another battery.
Q.4. The following circuit has a mistake and does not glow. Identify the mistake and make necessary changes to make the circuit working.
In the above circuit, the positive terminal of one battery is connected to the positive terminal of another battery. It should be connected in such a way that positive terminal of one battery is connected to the negative terminal of another battery.
Q.5.What are the effects of electric current? Name any two.
The effects of electric current are:
(i) It leads to heating and lighting.
(ii)It can convert straight conductor into a temporary conductor.
Q.6.When a compass needle is placed near the current carrying conductor, it gets deflected. Explain.
The needle gets deflected when it is kept near the current carrying wire due to the magnetic effect of the current. The needle of the compass is made up of thin magnet and when it comes in contact with the current carrying wire which also acts like a magnet, then the like poles repel each other and opposite poles attracts each other. Therefore the needle gets deflected.
Q.7. When the switch is closed in the circuit which is shown below, does the compass needle gets deflected??
The compass needle does not get deflected as there is no battery which is the source of current.
Q.8. Fill in the blanks:
(i) Long line symbol in the cell represents its __________ terminal.
(ii) Two or more cell combination is called __________.
(iii) When the room heater is switched ‘ON’, then it ___________.
(iv) The safety device which is present on the heating effect of electric current is_________.
Ans. (i) positive (ii) battery (iii) becomes red hot and emits heat (iv)fuse.
Q.9.State whether the following statement is true or false:
(i) To connect two cells to form a battery, the negative terminal is connected to the negative terminal of another cell.
(ii)When the electric current through the wire exceeds a certain limit, the fuse wire melts and breaks the circuit.
(iii)A piece of iron is not attracted by electromagnet.
(iv)Electromagnet is present in a electric bell.
Ans. (i) False (ii) True (iii) False (iv)True
Q.10. Does the electromagnet can be used to separate plastic bags from a heap of garbage? Explain.
Plastic bags can’t be separated from garbage using electromagnet. Plastic bags are not magnetic material, only materials like manganese are attracted by magnets.
Q.11. An electrician who is repairing your house wants to change the fuse with a piece of wire. Would you agree? Give reasons for your response.
No, we would not agree to it. If the current in the wire exceeds the melting point of the fuse, then the fuse wire melts and prevents short circuit. We should use ISI marked fuse to prevent short circuit.
Q.12. Mark made an electric circuit using cell holder, a bulb and a switch. The bulb didn’t glow when it is switch ‘ON’. Help Mark identify the defect in the circuit.
The cells should be connected properly. The positive terminal of one cell should be in series with the negative terminal of the other cell. The switch should be closed properly and a bulb which is not fused should not be used. Then, the bulb will glow certainly.
Q.13. When the switch is in ‘OFF’ position, will the bulb glow? In what order does the bulb X, Y and Z glow if the switch is turned ‘ON’?
The bulb X, Y and Z does not glow when the switch is in ‘OFF’ position.
When the switch is closed, all the bulbs will glow at the same time simultaneously.