This GCSE Physics quiz will challenge you on energy and efficiency. Energy efficiency saves money, energy and the environment. No device can be 100 percent efficient; during any energy transfer, some always escapes into the surroundings and is wasted. Wasted energy is usually in the form of heat but is sometimes sound or light. Filament light bulbs are only about ten percent efficient which means that they waste nearly all the energy that is fed into them. LED lighting is a good way of saving on energy as they are about 75 to 80 percent efficient. Petrol engines are usually between twenty and thirty percent efficient, diesel engines are more efficient than petrol engines but they still waste well over half of the energy supplied to them.
In electrical circuits, as the electrons flow through a conductor, energy is lost as they collide with the atoms of the conductor.