3.2 Electrical Power Flashcards
1
Q
What is the power of an appliance?
A
The rate at which is transfers energy
2
Q
What is powers unit?
A
Watt, W
3
Q
Why do we sometimes use kilowatts instead of watts?
A
Watts are too small a unit to be useful
4
Q
What is the equation for power?
A
P=e/t
Where
P is the power in watts
E is the energy transferred in joules
T is the time in seconds
5
Q
How can we work out the efficiency of power?
A
Efficiency = useful power out / total power in
x100 for a %
6
Q
What is 1 watt equivalent to?
A
1 joule per second
7
Q
An electric motor transfers 48kJ of electrical energy into kinetic energy in 2 minutes. What is the useful power out of the motor?
A
400W
8
Q
What is power?
A
The amount of energy transferred per second
