Power and Efficiency (Leaving Cert Physics): Flashcards

Rate at which work is done or energy is transferred

$P = \frac{W}{t}$

$P = \frac{E}{t}$

Watt (W)

James Watt

1 joule per second

How well a device converts input energy to useful output energy

$\frac{\text{Useful Power Output}}{\text{Power Input}} \times 100\%$

Speed or rate at which work is completed

Heat, sound, and friction

Work and energy transfer are equivalent concepts

LED bulb (42.9% vs 5%)

1000 watts