3.2 - Electrical power Flashcards
1
Q
What is the power of an appliance?
A
The rate at which it transfers electricity
2
Q
What is the unit of power?
A
watts, W
3
Q
How does the unit of power relate to the unit of energy?
A
An appliance with a power of 1 watt transfers 1 joule of electrical energy to other forms every second
4
Q
What is a kilowatt (kW) equal to?
A
1000 watts
5
Q
In the equation P=E/t, what is P?
A
The power in watts, W
6
Q
In the equation P=E/t, what is E?
A
The energy in joules, J
7
Q
In the equation P=E/t, what is t?
A
Time taken for the energy to be transferred in seconds, s
8
Q
Why can we write the equation for efficiency in terms of power?
A
Power is the energy per second transferred or supplied
9
Q
What is the equation for efficiency in terms of power?
A
Efficiency = useful power out/total power in (x100%)
