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Electric Current and its Effects
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)
(a) False
To make a battery of two cells, the negative terminal of one cell must be connected to the positive terminal of the other cell.
(b) True
The wire of the fuse is made of special material which has a low melting point. When large current passes through a fuse, it melts quickly and breaks the circuit.
(c) False
Working of an electromagnet is based on the magnetic effect of electric current. An electromagnet behaves as a magnet when current passes through it. Hence, it will attract a piece of iron.
(d) True
An electric bell has a piece of iron wound by a coil. When current passes through this coil, it behaves as an electromagnet.
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Name any two effects of electric current.
When the current is switched on through a wire, a compass needle kept nearby gets deflected from its north-south position. Explain.
Will the compass needle show deflection when the switch in the circuit shown by figure is closed?
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 _________.
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)
Do you think an electromagnet can be used for separating plastic bags from a garbage heap? Explain.
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.
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.
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?
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