Electrical Energy

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Fomulae

Power is the rate of energy transfer:

Power ( Watts ) = Energy Transferred ( J ) / Time ( Seconds )

1 Kilowatt = 1000 Watts

Using Joules as the units can lead to inconvenient, large numbers

Instead, we use kiloWatt- hours:

1 kiloWatt hours is equal to the energy used by a 1kW device for an hour

Energy ( kW-h ) = Power ( kw ) x Time ( Hours )

OR

Energy ( J ) = Power ( w ) x Time ( Seconds )

Cost = No. of kW-h x cost per kW-h

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Cost- Effectiveness

Most appliances have costs:

  • Installing
  • Running
  • Repairs

Cost- effectiveness means the best value for money

To compare cost-effectiveness, you need to take into account other factors, such as enviromental and running costs

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