Comparing power ratings and energy values
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What can you use to know how much energy an appliance uses
using its power rating
what is the power rating of an appliance
energy that it uses per second when operating at it’s max recommended power
what does the energy transferred depend on
the power rating
Complete the sentence the ………… the power rating the ……. energy transfers in a given amount of ……
The higher the power rating the more energy transfers in a given amount of time
how can you compare how much energy is transferred by appliances?
with different power ratings
how much energy is transferred by a 1.5 kW electric heater compared to a 4 kW electric heater, when they’re both left on for 1.5 hours
Energy transferred (kWh) = power rating (kW) x time (h) 1.5kW heater = 1.5 x 1.5 = 2.25 kWh 4kW heater = 4 x 1.5 = 6 kWh difference of both heaters = 6 - 2.25 = 3.75 kWh so the 4kWh transfers 3.75 kWh more energy
what is energy in food measured in
kilojoules (kJ)