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NCERT solutions Science Textbook for Class 7 chapter 14 Electric Current and Its Effects

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Chapter 14 - Electric Current and Its Effects

Pages 170 - 172

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

Q 1 | Page 170 | view solution

Draw the circuit diagram to represent the circuit shown in figure.

Q 2 | Page 170 | view solution

Figure 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.

Q 3 | Page 170 | view solution

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.

Q 4 | Page 170 | view solution

Name any two effects of electric current.

Q 5 | Page 170 | view solution

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

Q 6 | Page 171 | view solution

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

Q 7 | Page 171 | view solution

Fill in the blanks:

Longer line in the symbol for cell representsits_________terminal.

Q 8.1 | Page 171 | view solution

Fill in the blanks:

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

Q 8.2 | Page 171 | view solution

Fill in the blanks:

When current is switched ‘on’ in a room heater, it __________

Q 8.3 | Page 171 | view solution

Fill in the blanks:

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

Q 8.4 | Page 171 | view solution

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

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)

Q 9.1 | Page 171 | view solution

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

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

Q 9.2 | Page 171 | view solution

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

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

Q 9.3 | Page 171 | view solution

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

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

Q 9.4 | Page 171 | view solution

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

Q 10 | Page 171 | view solution

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.

Q 11 | Page 171 | view solution

Zubeda made an electric circuit using a cell holder shown in Figure, 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.

Q 12 | Page 171 | view solution

In the circuit shown in figure

1) Would any of the bulbs glow when the switch is in the ‘OFF’ position?

2) What will be the order in which the bulbs A, B and C will glow when the switch is moved to the ‘ON’ position?

Q 13 | Page 172 | view solution

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