# NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

Written by Team Trustudies
Updated at 2021-05-07

## NCERT solutions for class 7 Science Chapter 14 Electric Current And Its Effects Exercise

Q.1 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

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

Q.2 Draw the circuit diagram to represent the circuit shown in Fig.14.21.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

Q.3 Fig.14.22 shows four cells fixed on a board. Draw lines to indicate how you will connect their terminals with wires to make a battery of four cells.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

Q.4 The bulb in the circuit shown in Fig.14.23 does not glow. Can you identify the problem? Make necessary changes in the circuit to make the bulb glow.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) The bulb in the circuit is not glowing because the two cells are not connected properly.

(2) To make the bulb glow, the negative terminal of one cell should be connected to the positive terminal of the other cell, as shown in the given figure.

Q.5 Name any two effects of electric current.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

Two effects of electric current are :

(1) Heating effect of electric current

(2) Magnetic effect of electric current

Q.6 When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) The needle of a compass is a tiny magnet, which points in the north-south direction. When a magnet is brought close to it, the needle gets deflected.

(2) When an electric current passes through a wire, it behaves like a magnet.

(3) This magnetic effect of the electric current makes the compass needle deflect from the north-south direction.

Q.7 Will the compass needle show deflection when the switch in the circuit shown by Fig.14.24 is closed?

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) No, the compass needle does not show deflection when the circuit is closed, the magnetic field is not created until the current is flowing through the circuit.

(2) This circuit does not have a source of current like a battery in it.

Q.8 Fill in the blanks:
(a) Longer line in the symbol for a cell represents its __________ 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 ___________ .

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(a) Longer line in the symbol for a cell represents its positive terminal.

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

(c) When current is switched ‘on’ in a room heater, it produces heat .

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

Q.9 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)

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

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

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

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

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

Q.10 Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) No, electromagnets attract only magnetic substances.

(2) Plastic bags are non-magnetic in nature and are not attracted by an electromagnet.

(3) Hence, an electromagnet cannot be used for separating plastic bags from a garbage heap.

Q.11 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.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) It is not a wise idea to replace the fuse with a piece of wire, as it has a very low melting point.

(2) Every wire cannot be used as a fused filament.

(3) A fused filament must have a low melting point such that it could melt and break in response to a large amount of current.

(4) Most of the wires have high melting points and hence a wire cannot be used to replace the fuse.

(5) In the case of a metal piece, the melting point will be high and the circuit will be intact in case there is overload or overheat.

Q.12 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.

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects

(1) Rubber band used in the cell holder may not be tight enough to keep the two cells in contact with each other.

(2) Cell power has been exhausted.

(3) Maybe the two cells are not connected properly. The negative terminal of one cell must be connected to the positive terminal of the other cell.

(4) The connecting wire may be loose.

(5) The electric cell may be used up.

(6) Switch may not be functioning well.

Q.13 In the circuit shown in Fig. 14.25

(i) Would any of the bulb 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?

NCERT Solutions for Class 7 Science Chapter 14 Electric Current And Its Effects