Energy and Power in Electric Circuits – Practice


1) Calculate the work carried by 20C of charge with a potential difference of 100mV:

2) A dryer operating on a voltage of 240V draws a current of 30A. Calculate the power used by this dryer:

3) An oven is used for 2 hours. It operates at a potential difference of 90V to produce a current of 25A. How much energy is used in this time?

4) A 9V battery powers a toy that draws a current of 50mA. How long will this toy last for if it uses 2430J of energy before going flat?

Quick Answers:

1) 2J

2) 7200W

3) 1.62 × 107 J

4) 5400 sec (90 min)

Worked Answers: