P8.2.3 - The National Grid

Question 1

What is the National Grid?

Answer 1

A network of cables and pylons,​ that carry electricity generated in power plants to homes and businesses.​

Question 2

Why are transformers used?

Answer 2

To adjust the voltage to minimise power/energy loss as heat

Question 3

What do step-up transformers do?

Answer 3

It increases the voltage which decreases the current (less energy lost as heat)

Question 4

What do step-down transformers do?

Answer 4

It decreases the voltage which increase the current (appliances can run at home without problems)

Question 5

Why is electricity transferred through The National Grid at a much higher voltage than the voltage generated in a Power Station?​

Answer 5

If there is higher voltage, each electron carry more energy so fewer electrons are needed to carry the energy. There a fewer collisions between electrons and wire atoms so less heat energy is wasted

Question 6

Why do the powerlines supported by pylons have to be so high off the ground?

Answer 6

The power lines are at a high potential difference and so there is a high likelihood of current arcing to the ground.​

Question 7

Why do we need to use transformers in the National Grid?

Answer 7

• Current in wires waste energy by transferring some electrical energy as heat to the surroundings
• To reduce energy loss electricity is transferred at high voltage
• Increasing the voltage of the electrical energy, reduces the current
• Transformers are used to step up the voltage after a power plant and step down the voltage before homes/businesses