Flashcards in 3.2 Electrical Power Deck (8):
What is the power of an appliance?
The rate at which is transfers energy
What is powers unit?
Why do we sometimes use kilowatts instead of watts?
Watts are too small a unit to be useful
What is the equation for power?
P is the power in watts
E is the energy transferred in joules
T is the time in seconds
How can we work out the efficiency of power?
Efficiency = useful power out / total power in
x100 for a %
What is 1 watt equivalent to?
1 joule per second
An electric motor transfers 48kJ of electrical energy into kinetic energy in 2 minutes. What is the useful power out of the motor?