Mr. Dogra lives in a very old house. The electric wiring in this house was done more than 50 years ago. Mr. Dogra purchased an air conditioner recently. One day Mr. Dogra was sitting in a closed room with all his family members with air conditioner switched on. A geyser was also working on the same socket as the air conditioner. Suddenly, everyone in the room heard a little explosion and saw that the electric wires in the air conditioner socket had caught fire. Mr. Dogra was so shocked that he did not know what to do. Mr. Dogra's son Rajesh who is studying in Class X rushed out of the room and put off the main switch quickly. Before Mr. Dogra could call the Fire Brigade, Rajesh extinguished the fire with the help of a fire extinguisher which he had made in the school. An electrician was called. When he checked the main fuse, he found that someone had put a thick copper wire in the main fuse instead of proper fuse wire. The electrician changed the whole wiring of the house by using good quality wires and fixed a proper fuse wire in the main fuse. He also made separate circuit for geyser and provided separate fuses for all the circuits.
(a) Why did the electric wires catch fire ?
(b) What is the condition of using an air conditioner and a geyser on the same socket known as ?
(c) Why did the fuse not blow off ?
(d) What would you recommend in place of old porcelain fuse holders in the house to project the wiring more efficiently ?
(e) What values are displayed by Mr. Dogra's son Rajesh in this whole episode ?

Explanation

(a) The wires caught fire due to overheating caused by the excessive current passing through then when two appliances, air conditioner and geyser, which draw heavy current were used on the same socket.
(b) This condition is called overloading.
(c) The fuse did not blow off because a thick copper wire had been used as a fuse wire in the fuse box which did not get heated too much, did not melt and hence did not break to cut off the electric supply.
(d) The old porcelain fuse holders should be replaced by MCBs (Miniature Circuit Breakers). And an additional MCB should be put inthe air conditioner circuit alongwith its socket.
(e) The values displayed by Mr. Dogra's son Rajesh are (i) Presence of mind (in switching off the main switch to cut off electricity supply and prevent fire from spreading), and (ii) Concern for the family (to protect them by extinguishing the fire).