Energy and Thermal Physics

Maximum power and operating power

Teaching Guidance for 11-14 Supporting Physics Teaching

Maximum power

Wrong Track: The Rolls-Royce has a power of 338 kilowatt.

Right Lines: The maximum power output for the Rolls-Royce is 338 kilowatt.

Interpreting the figures

Thinking about the teaching

When comparing the power figures of appliances, it is important to stress the point that the figures quoted need to be correctly interpreted. For the Rolls-Royce, 338,000 joule / second is the maximum energy cost per second. The car can, of course, be driven much more carefully so that the energy cost per second is much lower. On the other hand, the power figures for kitchen appliances such as kettles and fridges are likely to be fixed at their normal operating power.

appears in the relation P=VI P=I^2R P=V^2/R ΔQ=PΔt
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