Page 57 - Innovator's Science-8

10. Neha keeps the coil the same way as in given below but slides
the iron nail out, leaving only the coiled wire. Will the coil s ll
deflect the compass? If yes, will the deflec on be more or less
than before?
Ans. Yes, the coil will s ll make the compass needle move even a er
the iron nail is removed. This is because the coil itself becomes
a magnet when electric current flows through it. The iron nail
only makes the magnet stronger, so when Neha removes it, the (b) Coil and magnetic compasses;
(c) Coil connected to a cell;
magnet becomes weaker, and the compass needle moves less. (d) Coil with iron nail inserted;
(e) Coil with iron nail and clips
11. We have four coils, of similar shape and size, made up from iron, copper, aluminium, and nichrome as
shown in the Figure:

Iron Copper Aluminium Nichrome

a. b. c. d.
When current is passed through the coils, compass needles placed near the coils will show deflec on.
i. Only in circuit (a) ii. Only in circuits (a) and (b)
iii. Only in circuits (a), (b), and (c) iv. In all four circuits
Ans. The compass needles near the coils will move in all four cases, but not by the same amount. This is
because the strength of an electromagnet depends on the material used inside the coil. Materials like
iron, nickel, and cobalt make very strong electromagnets, while metals like aluminum or nichrome of the
same size will make weaker ones. So, the compass needle will move more when the magnet is stronger
and less when it is weaker.

Put on your
Thinking cap Problem Solving Skills

A. Darken the correct options in the OMR Sheet:

1. Wires made of which of the following materials is more suitable for OMR Sheet
showing the heating effects of electric current?
a. Copper wire b. Nichrome
c. Aluminium d. Silver
2. Which of the following appliances is based on the magnetic effects of Wrong Methods

electric current.
Correct Method
a. Electric Iron b. Electric bell
c. Water heater d. Electric Stove
1. a b c d
3. Voltaic cell uses ___________ electrolyte that is why it is not considered as
2. a b c d
convenient as a dry cell.
a. coloured b. solid 3. a b c d
c. liquid d. paste

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Science-8