A heater has an electrical input of 1000 J and produces 320 J of useful heat. What is its efficiency and how much energy is wasted?

A heater has an electrical input of 1000 J and produces 320 J of useful heat. What is its efficiency and how much energy is wasted?

• A. Efficiency = 0.68; wasted energy = 320 J
• B. Efficiency = 0.32; wasted energy = 680 J
• C. Efficiency = 0.32; wasted energy = 320 J
• D. Efficiency = 0.50; wasted energy = 180 J

Answer: (B)