Ch-12 Electricity (Question) Page220

Question 1:	What determines the rate at which energy is delivered by a current?
Answer :	The rate of consumption of electric energy in an electricappliance is called electric power. Hence, the rate at which energy is delivered by a current is the power of the appliance.
Question 2:	An electric motor takes 5 A from a 220 V line. Determine the power of the motor and the energy consumed in 2 h.
Answer :	Power (P) is given by the expression, Where, Voltage, V = 220 V Current, I = 5 A Energy consumed by the motor = Pt Where, Time, t = 2 h = 2 × 60 × 60 = 7200 s  P = 1100 × 7200 = 7.92 ×106 J Therefore, power of the motor = 1100 W Energy consumed by the motor = 7.92 × 106 J