# NCERT Solutions for Class 7 Science Chapter 14

## Electric Current and its Effects Class 7

### Exercise : Solutions of Questions on Page Number : 170

Q1 :

Draw in your notebook the symbols to represent the following components of electrical circuits: connecting wires, switch in the 'OFF' position, bulb, cell, switch in the 'ON' position, and battery.

 Component of electrical circuit Symbol Connecting wires Switch in the 'OFF' position Bulb Cell Switch in the 'ON' position Battery

Q2 :

Draw the circuit diagram to represent the circuit shown infigure.

In the given circuit, one terminal of the bulb is connected with one terminal of the cell while their other terminals are connected to a safety pin. However, the safety pin is not connected with one of the drawing pins. Thus, the circuit is not complete. Hence, safety pin represents a switch in 'OFF' position. The circuit diagram of the given figure is shown in the following figure.

Q3 :

The bulb in the circuit shown in Figure does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.

Q4 :

Name any two effects of electric current.

Q5 :

When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.

Q6 :

Will the compass needle show deflection when the switch in the circuit shown by figure is closed?

Q7 :

Fill in the blanks:

(a) Longer line in the symbol for cell representsits_________terminal.

(b) The combination of two or more cells is called a _________.

(c) When current is switched 'on' in a room heater, it __________.

(d) The safety device based on the heating effect of electric current is called a _________.

Q8 :

Mark 'T' if the statement is true and 'F' if it is false:

(a) To make a battery of two cells, the negative terminal of one cell is connected to the negative terminal of the other cell. (T/F)

(b) When the electric current through the fuse exceeds a certain limit, the fuse wire melts and breaks. (T/F)

(c) An electromagnet does not attract a piece of iron. (T/F)

(d) An electric bell has an electromagnet. (T/F)

Q9 :

Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.

Q10 :

An electrician is carrying out some repairs in your house. He wants to replace a fuse by a piece of wire. Would you agree? Give reasons for your response.

Q11 :

Zubeda made an electric circuit using a cell holder shown in Fig. 14.4, a switch and a bulb. When she put the switch in the 'ON' position, the bulb did not glow. Help Zubeda in identifying the possible defects in the circuit.

Q12 :

In the circuit shown in figure

(i) Would any of the bulbs glow when the switch is in the 'OFF' position?

(ii) What will be the order in which the bulbs A, B and C will glow when the switch is moved to the 'ON' position?