Answer:
a) Energy is used by the light bulb when it is used for 4 hours:1,440,000 Joules.
b) Energy is used by the microwave when it is used for 5 minutes:360,000 Joules
c)1,414,080 Joules of heat energy will be produced by light bulb in 4 hours.
Explanation:
Power is defined as ratio of work done per unit time.
Power of light bulb,P = 100 W
Power of microwave,P' = 1200 W
a) Energy is used by the light bulb when it is used for 4 hours:
Duration of time it is used = T = 4 hours =14,400 s
b) Energy is used by the microwave when it is used for 5 min:
Duration of time it is used = T' = 5 min = 300 sec
c) Heat energy produced by light bulb with an efficiency of 1.8%.
Efficiency 1.8% means that light bulb gives 1.8 % of its energy into light energy remaining as heat energy.
Heat energy produced by light bulb = 100% - 1.8 % = 98.2 %
Energy used by the bulb in 4 hours = 1,440,000 J
Heat energy produced by light bulb = 98.2% of 1,440,000 J:
1,414,080 Joules of heat energy will be produced by light bulb in 4 hours.