Practice Questions

1.Describe the journey of electricity from a power station to our homes.

Electricity from the power station will pass through a step up transformer which increases the potential difference from 25,000V to 400,000V. 

Electricity is then transmitted as a high potential difference, low current.

Finally, the electricity will pass through a step down transformer to decrease the potential difference from 400,000V to 230V to supply homes. 

2. Explain the advantage of transmitting electricity as a high potential difference, low current.

Keeping the potential difference high, means that the current is low. 

A low current makes the transmission of electricity more efficient.

3. A current through a wire is doubled, predict how this would affect the power loss in terms of heat from the wire.

Power = Current² x Resistance

If the current is doubled and this is a squared quantity, then the power will multiply by 2² or 4.