P1.3 Electrical energy

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  • P1.3 Electrical Energy
    • kWh is a unit of energy. This is the energy supplied to a 1 kW appliance in 1 hour
    • The more powerful the appliance, the faster the rate at which it transfers energy.
    • Watt - rate of transfer of energy of 1 joule per second (J/s)
    • Energy (J) = Power (W) * Time (s)
    • 1 Kilowatt = 1000W
    • When a battery is connected to a light bulb, electrical energy is transferred from the battery to the light bulb. The filament of the light bulb becomes hot and so energy transfers to the surroundings by heating and as light energy
    • Power - energy transferred or transformed per second. The unit of power is the Watt (W)
    • Efficiency = (useful power out/ total power in) *100%
    • Total cost= number of kWh used*cost per kWh
    • Cost effectiveness = getting the best value for money


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