P3 Energy and Power In Circuits

Question 1

Work done per unit of charge is also referred to as what?

Answer 1

Potential difference

Question 2

What is the formula for work done (energy transferred)?

Answer 2

Work done (energy transferred) (Q) = charge (A) x potential difference (V)

Question 3

The rate of transfer is also known as what?

Answer 3

Power (watts ‘w’)

1 watt = 1 joule/sec

Question 4

What formula is used to calculate power?

Answer 4

Power (W) = energy (J) / time (s)

Question 5

What are the two equations that can be used to calculate the power of a circuit?

Answer 5

1 - power (W) = potential difference (V) x current (A) P=VI

2 - power (W) = Current (squared) (A2) x resistance (ohms) P=I2R

Question 6

A 1.5 x10(to the power of 3) W hairdryer is turned on for 11 minuets. Calculate the energy transferred?

Answer 6

11 x 60 = 660 sec
1.5 x 10(to the power of 3) v 1500w
Energy transferred = power x time 
= 1500 x 660
= 990,000 J