Electrical Energy in Devices

What has to happen whenever a charge flows?

• Has to overcome the resistance of the circuit, requires energy therefore:

  • Work is done when charge flows

  • Amount of work done depends on the amount of charge that flows & potential difference

How can you find the amount of energy transferred?

energy transferred = power x time E = Pt energy transferred= charge flow x potential difference E = QV

What are electrical appliances designed to do?

• Cause energy transfers

• Type & amount of energy transferred between stores depends on appliance

What is the National Grid?

A system of cables and transformers linking power stations to homes and businesses

What is a power station?

• Transfers the energy supply into electrical energy

• Using small number of large power stations more efficient than many small power stations- large stations made more efficient

• Most power plants use steam turbines, more efficient at higher steam temps - bigger plant, bigger boiler, higher steam temp.

What is a step-up transformer?

• Increase the potential diff. from power station to transmission cables

• Reduces the current, reduces heating effect caused by current flowing in transmission cables

  • Reduces energy loss, makes transmission more efficient

What are transmission cables?

• Transfer the electricity

What is a step-down transformer?

• Reduce potential diff. from the transmission cables to much lower value for domestic use