# Can someone please help me with my physics?

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I am in year 9 and doing my Core AQA gcse practice exams.

I need help on electrical energy transfers (e.g the formulas and stuff) i dont understand my teacher and i need to understand it soon!

## 3 Answers

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First of is the simple stuff found in AQA Physics Unit 1

Electrical devices transform electrical energy, some of this energy is used as useful energy, some is lost as wasted energy

For example: A hair dryer gives off heat energy which is useful for the hair dryers purpose, but the hair dryer also generates sound energy which is lost as wasted energy

The power of a device is the rate at which it transforms energy

Power is measure in Watts, W. A device with a power of 1 watt transforms 1 joule of energy to other energy every second.

Watts are very small and not particularly powerful so they are often used as Kilowatts, kW.

1kW = 1000W

The Equation for Power is:

Power (In watts) = Energy transferred (in joules) DIVIDED BY Time taken (In seconds)

Companies that supply electricity charge people on the amount of electrical energy used. This is measured in Kilowatt-hours, kWh. This is measured by the amount of energy that is transferred by a one kilowatt device that is used in an hour.

The Equation for Kilowatt-hour is:

Energy transferred (kWh) = Power of device (kW) X Time (h)

Total cost of electricity =Number of kWh X Cost per kWh

Thats all on Electrical transfers and calculations for Core Physics on the AQA Spec

Hope it helped :)

Luke

- 0 votes

First of is the simple stuff found in AQA Physics Unit 1

Electrical devices transform electrical energy, some of this energy is used as useful energy, some is lost as wasted energy

For example: A hair dryer gives off heat energy which is useful for the hair dryers purpose, but the hair dryer also generates sound energy which is lost as wasted energy

The power of a device is the rate at which it transforms energy

Power is measure in Watts, W. A device with a power of 1 watt transforms 1 joule of energy to other energy every second.

Watts are very small and not particularly powerful so they are often used as Kilowatts, kW.

1kW = 1000W

The Equation for Power is:

Power (In watts) = Energy transferred (in joules) DIVIDED BY Time taken (In seconds)

Companies that supply electricity charge people on the amount of electrical energy used. This is measured in Kilowatt-hours, kWh. This is measured by the amount of energy that is transferred by a one kilowatt device that is used in an hour.

The Equation for Kilowatt-hour is:

Energy transferred (kWh) = Power of device (kW) X Time (h)

Total cost of electricity =Number of kWh X Cost per kWh

Thats all on Electrical transfers and calculations for Core Physics on the AQA Spec

Hope it helped :)

Luke

- 0 votes

Thanks! Yeah, big help and i can refer back to it now! :) muchly appriciated (well, i cant spell it, but you know what I mean) XD