National Grid Flashcards
What is the National Grid
A system of transformers and high voltage cables
Problem in cables
Energy is always lost due to resistance
One way to reduce energy lost
Building power stations near homes
What does a step up transformer do
Increases potential difference
Why is the P.D increased
Less energy is lost in power cables
What do step down transformers do
Reduce potential difference to 230 V
Why would the national Grid not work at a maximum
Conserve fuel reserves
Spare capacity in case of an emergency shut-down
Explain why people get electric shock if they touch live wire
Potential difference of wire 230v. potential difference of electrician 0v. So large p.d between the two. Current passes through body
When a negatively charged student touches a metal tap and receives an electric shock why?
There is a potential difference between them. Which causes electrons to transfer from the student. Which earths the charge.
Some carpets have thin copper wires running through them. The student is less likely to receive an electric shock after walking on this type of carpet. Why?
Copper has a lower resistance
No build up of charge
When electric cars are not being driven, energy stored in their batteries could be used to meet sudden peaks in electricity demands.
When cars plugged in the energy from the car batteries could be transferred back to national grid
Frequency
50 Hz
When the voltage increase the current
Decreases
Vic versa
