Rajan constructed a small house. He used good quality and well insulated copper wires for wiring. He also used good quality switches, sockets and plugs. However, had a very old room heater. On one winter night, Rajan was sleeping in a closed room with his family with the room heater switched on. During sleep, Rajan felt suffocated and woke up to see the room heater on fire. Rajan's son Arvind got up quickly and put off the main switch. Arvind also made a telephone call to Fire Brigade. The Fire Brigade men reached quickly and extinguished fire in the room. Rajan and his family thanked the firemen.
(a) What was the cause of fire in Rajan's house ?
(b) Name the safety device which was missing in the electric wiring of Rajan's house ?
(c) How could the above device prevent fire in Rajan's house ?
(d) What values are displayed by Arvind in this whole incident ?

Explanation

(a) The cause of fire in Rajan's house was short-circuiting (due to the working of an old room heater having connecting cord with torn insulation, etc.).
(b) Electric fuse is the safety device which was missing in the wiring of Rajan's house.
During short-circuiting, when the live wire and neutral wire touch each other directly, then the resistance of the circuit formed becomes very low due to which too much current passes through fuse wire, the fuse wire gets heated too much, melts and breaks, cutting off the electricity supply in the household circuit. This prevents the electric fire in the house.
(d) The values displayed by Arvind in this incident are (i) General awareness (that electric fire can be prevented from spreading by putting off the main switch), and (ii) Presence of mind (in calling the Fire Brigade to extinguish fire).