AQA GCSE FOUNDATION PHYSICS - The National Grid and Transformers

The National Grid and Transformers

The National Grid is a network of power lines that carry electricity from power stations to homes and businesses across the country. It's essential for our modern way of life, providing the electricity we need to power everything from lights and appliances to computers and transportation.

The Importance of Transformers

One of the key components in the National Grid is the transformer. Transformers are essential for efficient electricity transmission, enabling us to transport power effectively over long distances.

Why do we need transformers?

• Power loss during transmission: When electricity flows through wires, some energy is lost as heat due to resistance. This loss is proportional to the current flowing through the wire.
• High current, high losses: A high current flowing through the wires leads to significant energy loss.
• Transformers to the rescue: By increasing the voltage and decreasing the current, transformers reduce energy loss during transmission.

Step-Up Transformers

• Function: Step-up transformers increase the voltage of electricity.
• Location: Step-up transformers are located near power stations.
• Why they're important: By increasing the voltage, step-up transformers reduce the current, minimizing energy loss during transmission.

Step-Down Transformers

• Function: Step-down transformers decrease the voltage of electricity.
• Location: Step-down transformers are located close to homes and businesses.
• Why they're important: By decreasing the voltage, step-down transformers make the electricity safe to use in homes and businesses.

How Transformers Work

Transformers use the principle of electromagnetic induction to change the voltage of electricity.

1. Primary coil: An alternating current (AC) flows through the primary coil.
2. Magnetic field: This creates a changing magnetic field around the coil.
3. Secondary coil: The changing magnetic field cuts through the secondary coil.
4. Induced current: This induces an alternating current in the secondary coil.

The voltage in the secondary coil is determined by the ratio of turns in the primary and secondary coils:

• Step-up transformer: More turns in the secondary coil than the primary coil.
• Step-down transformer: Fewer turns in the secondary coil than the primary coil.

Summary

• National Grid: A vast network of power lines delivering electricity across the country.
• Transformers: Essential devices for efficient electricity transmission by changing the voltage.
• Step-up transformers: Increase voltage, reduce current, minimize energy loss during transmission.
• Step-down transformers: Decrease voltage, make electricity safe for use in homes and businesses.
• Electromagnetic induction: The principle underlying the operation of transformers.