An LCD TV has an efficiency of 0.28. Energy is supplied to it at a rate of 110 W. If the TV is left on for 90 minutes, how much energy is wasted? Give your answer to 2 significant figures.
A machine has a useful power output of 400 W and a total power input of 1 600 W. In a given time, the total energy supplied to the machine is 108 kJ. What is the useful output energy transfer of the machine at this time?
A 100 W incandescent light bulb has an efficiency of . What is the useful power output of the light bulb?