An electric iron is rated 220V, 2 kW.
(i) If the iron is used for 2h daily, find the cost of running it for one week if it costs ₹4.25 per kWh.
(ii) Why is the fuse absolutely necessary in a power circuit?
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Given,
power P = 2 kW,
time t = 2h,
number of days = 7 and cost = ₹4.25 per kWh
Electrical energy consumed = Power x total time
= 2 kW x (2 x 7) h
= 28 kWh
Cost = 28 x 4.25 = ₹119
∴ Cost of running the iron for a week is ₹119
(ii) The appliances connected to the power circuit like air conditioner, geyser, washing machine, etc. consume heavy current. The fuse is absolutely necessary in a power circuit because if somehow the circuit is overloaded (i.e., the total power of appliances connected in the circuit exceeds the power limit of the circuit) an excessive current will flow in the circuit and the line wire or appliances may get damaged. Moreover, due to the excessive heat produced by such high current, the wires may get overheated causing a fire. The use of fuse in power circuit will safe guard against any such mishap.