Farid was given two thin wires X and Y in the science laboratory. The teacher asked Farid to find out (by performing suitable activities) which wire was 'fuse wire' and which one a 'nichrome wire'. Farid was given batteries of 3 V and 12 V, and some copper connecting wires alongwith crocodile clips. The teacher had himself performed this activity earlier and knew that the batteries of 3 V and 12 V were appropriate for this activityc. The teacher also advised Farid ot put off fan while performing the activites and take necessary precautions to avoid burns. Farid performed the activities and concluded that wire X is nichrome wire whereas wire Y is the fuse wire.
(a) Describe briefly the activity which Farid could have performed to conclude that wire X is nichrome wire.
(b) Describe briefly the activity which Farid could have performed to conclude that wire Y is fuse wire.
(c) Why did teacher advise Farid to switch off the fan during these activities ?
(d) What values are shown by Farid in performing these activities ?

Explanation

(a) Farid first connected the wire X in series circuit with 3 V battery. He found that the wire got heated and became dull red. Farid then connected wire X in series circuit with 12 V battery. He found that wire X got heated too much and started glowing bright red. This showed that wire X is like the heating element of an electric heater and hence made of nichrome.
(b) Farid now connected the wire Y in series circuit with 3 battery. The wire got heated a little but did not glow. Farid then connected wire Y in series circuit with 12 V battery. He found that wire Y got heated too much, melted and broke into two pieces. Now, when a thin wire gets heated too much and breaks on passing excessive electric current, it behaves like a fuse wire. So, wire Y is the fuse wire.
(c) The teacher advised Farid to switch off the fan while performing these activities because the fan's air could cool the hot wires due to which the fuse wire will not get heated to its melting point and hence not break.
(d) The values shown by Farid in performing these activities are (i) Knowledge of the heating effect of electric current and working of fuse, and (ii) Ability to apply knowledge in real life situations.