Ch-13 Magnetic Effects of Electric Current (Question) Page238

Question 1:	Name two safety measures commonly used in electric circuits and appliances.
Answer :	Two safety measures commonly used in electric circuits and appliances are as follows: (i) Each circuit must be connected with an electric fuse. This prevents the flow of excessive current through the circuit. When the current passing through the wire exceeds the maximum limit of the fuse element, the fuse melts to stop the flow of current through that circuit, hence protecting the appliances connected to the circuit. (ii) Earthing is a must to prevent electric shocks. Any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.
Question 2:	An electric oven of 2 kW is operated in a domestic electric circuit (220 V) that has a current rating of 5 A. What result do you expect? Explain.
Answer :	Current drawn by the electric oven can be obtained by the expression, P = VI Where, Current = I Power of the oven, P = 2 kW = 2000 W Voltage supplied, V = 220 V Hence, the current drawn by the electric oven is 9.09 A, which exceeds the safe limit of the circuit. Fuse element of the electric fuse will melt and break the circuit.
Question 3:	What precaution should be taken to avoid the overloading of domestic electric circuits?
Answer :	The precautions that should be taken to avoid the overloading of domestic circuits are as follows: (a) Too many appliances should not be connected to a single socket. (b) Too many appliances should not be used at the same time. (c) Faulty appliances should not be connected in the circuit. (d) Fuse should be connected in the circuit.