1 Name two safety measures commonly used in electric circuits and
appliances.
2 An electric oven of 2 kW power rating is operated in a domestic electric
circuit (220 V) that has a current rating of 5 A. What result do you
expect? Explain.
3 What precaution should be taken to avoid the overloading of domestic
electric circuits?
Answers
1. Name two safety measures commonly used in electric circuits and
appliances.
1. Electric Fuse: An electric fuse is connected in series it protects the circuit from overloading and prevents it from short-circuiting.
2. Proper Earthing of an all-electric circuit in which any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.
2. An electric oven of 2 kW power rating is operated in a domestic electric
circuit (220 V) that has a current rating of 5 A. What result do you
expect? Explain.
Given,
Power = 2kw = 200w, current = 5A, voltage = 220V
So, power = Current * Voltage
Current = Power/Voltage = 200/220 = 9A
Thus the current will exceeds and the fuse will burn out if there is no fuse then overloading will cause melting of wires which will cause the short circuit which will cause a fire.
3. What precaution should be taken to avoid the overloading of domestic
electric circuits?
Following precautions should be taken to avoid the overloading of domestic circuits:
(a) Do not use too many appliances at the same time.
(b) Use the appliances within the safe limit of electric circuit.
(c) Do not connect too many appliances in a single socket.
Explanation:
Q. No 1: Name two safety measures commonly used in electric circuits and appliances.
Ans: Two safety measures commonly used in electric circuits and appliances are
(i) Electric Fuse: An electric fuse is connected in series it protects the circuit from overloading and prevents it from short circuiting.
(ii) Proper earthing of all electric circuit in which any leakage of current in an electric appliance is transferred to the ground and people using the appliance do not get the shock.
Q. No 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.
Ans: In this problem we have
Power of the oven (P) = 2 kW = 2000 W
Potential Difference (V) = 220 V
We have P = VI
⇒I=P/V
= 2000/220
= 9.09A
Here the current drawn by the electric oven is 9.09 A, which exceeds the safe limit of the circuit that is 5A. Therefore electric fuse will melt and break the circuit.
Q. No 3: What precaution should be taken to avoid the overloading of domestic electric circuits?
Ans: Following precautions should be taken to avoid the overloading of domestic circuits:
(a) Do not use too many appliances at the same time.
(b) Use the appliances within the safe limit of electric circuit.
(c) Do not connect too many appliances in a single socket.
(c) Fuse should be connected in series in the circuit to protect overloading and short circuiting.