P1aL9 Why Use Electricity?

Key Words

Battery (more correctly cell) -  a device that stores chemical energy and converts it to electrical energy when connected to a circuit.

Biomass - material from living organisms.

Chemical Energy - energy from chemical reactions.

Electrical Energy - transfer of energy by movement of electrons.

Mains Electricity - electricity generated in a power station and distributed to customers

Potential energy - stored energy that can be used to do a useful job of work.

Solar energy - energy from the Sun

Test Yourself

Homework
Physics GCSE
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Grade E

We use electricity to do a whole range of jobs.  Mains electricity is distributed to our homes:

  • It's safe (as long as you don't mess about with it);
  • It's clean;
  • It's reliable (power cuts are rare);
  • It's convenient.

We convert the electricity into other forms of energy, for example a hair-dryer converts electricity into heat and kinetic energy.

Many devices are powered by batteries.  These enable a low powered device like an MP3-player to be carried about.  However batteries can only store a small amount of energy as chemical energy.  When the battery is connected to the circuit, the chemical reaction occurs.  When the chemical reaction is complete, the battery goes flat.  Some batteries are rechargeable.  This means that the chemical reaction can be reversed by applying a current.

Items that need large amounts of power don't use batteries.  They are plugged into the mains.  Despite the claims of manufacturers, cordless tools are rarely as powerful as the mains (corded) tools.  If they were, be batteries would go flat within a couple of minutes.

Grade C

It is possible to use alternatives to electricity.  Biomass such as wood can be used to provide heat in a wood-burning stove.  Gas can provide light as well as heat.  Candles and paraffin lamps were used before mains electricity came along.

These methods are dirty and smelly (and potentially more dangerous).  Electricity is clean, although power stations give out a lot of pollution (but far less than if we all used coal, wood, and candles).

Electricity does much more interesting things.  While it is technically possible to have a gas-powered hoover, the same would not be possible with a television set!  You can imagine what life would be like without electricity.

In some places in the world, where there is no mains electricity and batteries are hard to get, wind-up radios are available.  These use potential energy in a spring to drive a tiny generator that charges up rechargeable batteries.

Also solar power can be used, to provide a small current for a device like a calculator.

Grade A

Light emitting diodes are semi-conductor devices that give out light when a current flows through them.  When electrons are moved away from the nucleus in an atom they gain energy.  They are excited.  When they fall back they give out a little piece of light called a photon.  The colours are determined by how excited the electrons are.

Light emitting diodes are now very widely available, and can give out impressive light levels.  Modern railway signals use arrays of LEDs that show red, yellow, and green using the same array of LEDs.

LEDs are more reliable than ordinary light bulbs, and use much less power.