National grid

Question 1

What is the job of a step-up transformer and why does it need to do it?

Answer 1

• Increases the voltage (to around 400,000 V) and decreases the current
• Power = voltage x current therefore, high power results in high current. However, high current leads to high resistance which leads to a lot of energy lost to the surrounding via heat. Therefore, to increase the efficiency of power transfer, we must decrease the current by increasing the voltage (power will remain the same)

Question 2

What is the job of a step-down transformer and why do we need it?

Answer 2

• Increases current and decreases voltage (to 230 V)
• Necessary because high voltage is very dangerous and can blow up household appliances