Power And Electrical Energy Flashcards
0
Q
What is the unit of power?
A
Watts.
1
Q
Define “power”.
A
Rate of transfer of energy.
2
Q
What is the equation used to calculate power?
A
Power = energy/time
3
Q
What are the units of the following:
A) power
B) energy
C) time
A
A) watts
B) joules
C) seconds
4
Q
What is the equation for calculating power in electrical circuits?
A
Power = potential difference x current
5
Q
Why is a high current needed for a starter motor in a motor car?
A
The power produced by a starter motor needs to be very high as it needs to provide a lot of energy in a very short time to rotate the engine to set it off. However, the potential difference across the starter motor (provided by the battery) is usually very small. As P=VI, the current flowing through the motor needs to be very high.
