Usefulness of electrical appliances 0.0 / 5 ? PhysicsElectricityGCSEAQA Created by: Megan1404Created on: 13-03-16 15:14 What is the formula for calculating the energy transferred by an appliance? What are the units? Energy = Power x Time, kWh, kW, hrs 1 of 5 What is the formula for calculating the cost of using a device? Total cost = no. of kWhs x cost per kWh 2 of 5 A 3kW electric motor is switched on for 15 mins. How much energy does it transfer during this time? E = P x t E = 3 x 0.25 E = 0.75kWh 3 of 5 1 kWh of energy costs 8p. On one day 30kWh of electricity were used - how much would this cost? 30 x 8 = 240p/£2.40 4 of 5 During the week a 2kW iron was used for 2.5 hrs. How much energy was transferred? 2 x 2.5 = 5kWh 5 of 5
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