What useful energy transfer takes place in an electric drill ?

Which electrical appliance is usefully transfers electrical energy into light energy and sound energy ?

How many watts are equivalent to 12 kilowatts ?

An electric motor transfers 48 kj of electrical energy into kinetic energy in 2 minutes. What is the useful power output of the motor ?

How much electrical energy, in kWh, is transferred when a 9 kW shower is used for 15 minutes ?

The price of 1 kWh of electrical energy is 9p. How much does it cost to use a 60 W electric light for 4 hours ?

what might environmental costs include ?

loft insulation costs £600 including installation. It saves £80 a year on the fuel bill. How long is the payback time ?