Page 154 - Physics Coursebook 2015 (A level)

Cambridge International AS Level Physics
12 Some electricity-generating companies use a unit called the kilowatt-hour (kW h) to calculate energy bills. 1 kW h is the energy a kilowatt appliance transfers in 1 hour.
a Showthat1kWhisequalto3.6MJ. [2]
b An electric shower heater is rated at 230 V, 9.5 kW.
i Calculate the current it will take from the mains supply. [2]
ii Suggest why the shower requires a separate circuit from other appliances. [1]
iii Suggestasuitablecurrentratingforthefuseinthiscircuit. [1]
c Calculate the energy transferred when a boy uses the shower for 5 minutes. [2]
142