national grid

National Grid

A network of cables and transformers that distributes electricity from power stations to homes and industry.

High voltage transmission

To reduce current in the cables, which minimizes energy lost as heat due to resistance.

Energy loss due to current

Energy loss = I² × R; higher current → more energy lost as heat.

Step-up transformer

A device that increases voltage for efficient transmission across long distances.

Step-down transformer

A device that reduces voltage to safe levels for domestic or industrial use.

Efficiency of the National Grid

Lower current reduces heating of cables (I²R losses) → less wasted energy.

Energy transfer in the National Grid

It shows energy transfer: chemical/nuclear → electrical → useful energy in homes, while highlighting efficiency and losses.

Example of energy loss

Cables heat up due to resistance; some energy is wasted as thermal energy.

Role of transformers

To change voltage levels for efficient transmission and safe domestic use.

Common misconception about high voltage

High voltage is safer and more efficient for long-distance transmission because current is lower.