6.4 Electrical Power and Potential Difference.

Can you match these quantities to their units?

Current Ohms

Resistance Coulombs

Power Amps

Voltage Watts

Charge Volts

April 20, 2023

6.4 Electrical Power and Potential Difference.

Answers

Current Amps

Resistance Ohms

Power Watts

Voltage Volts

Charge Coulombs

April 20, 2023

6.4 Electrical Power and p.d.

• The Power of an electrical device is the amount of energy it transfers every second.

• The Power depends on the current and potential difference (Voltage)

April 20, 2023

In the USA the Voltage is 110V. What would happen if you plugged a UK device into this Voltage? What might happen if an American plugged their device into the UK mains?

Page 190 AQA Physics

Power

• Power = Energy transferred (Joules, J)Time (seconds, s)(Watts, W)

E.g A light bulb uses 6000J of energy in 1 minute. How powerful is the bulb?

Power = ? Energy = 6000J Time = 1 minute = 60s

Power = 6000 / 60

Power = 100 Watts

Questions

1) An electric heater uses 3600000J in one hour. How much power does it use?

2) A car engine is rated at 100kW. How much energy does it use in 1s, 1min and 1 hour?

Page 190 Question a)

A pacemaker controls the beat of the heart. These contain explosive materials. If a body is cremated the pacemaker will explode in the incinerator causing quite a bit of damage and a really loud bang – not what you’d want at a funeral!

Electrical Power

Power = Current x Potential Difference

Watts, W Amperes, A Volts, V

E.g. What power is used by a 12V, 5A car bulb?

Power = 5A x 12V = 60 Watts

Answer Question b) p191. Then Question 2 in the summary questions