The unit of energy is the joule. One joule is the work done or energy required to exert a force of one newton for a distance of one metre. Putting that into more everyday terms, a joule of energy is the same amount of energy that you would use up lifting an orange off the floor onto your kitchen table.

A joule is actually a fairly small amount of energy, so it is usual to express energy measurements as kilojoules, where one kilojoule is 1000 joules.

It takes 216 kilojoules to heat a 60 watt light bulb for an hour and 280 kilojoules to walk a distance of one kilometre on flat ground (more if the journey is uphill). A massive 740 kJ would be required to climb a mountain the size of Ben Nevis.

The term joule is named after the man whose experiments first defined its value - James Prescott Joule.

A joule is actually a fairly small amount of energy, so it is usual to express energy measurements as kilojoules, where one kilojoule is 1000 joules.

It takes 216 kilojoules to heat a 60 watt light bulb for an hour and 280 kilojoules to walk a distance of one kilometre on flat ground (more if the journey is uphill). A massive 740 kJ would be required to climb a mountain the size of Ben Nevis.

The term joule is named after the man whose experiments first defined its value - James Prescott Joule.