National Grid Flashcards
(16 cards)
What is the potential difference and frequency of UK mains electricity?
230 V and 50 Hz
What is the difference between direct and alternating current?
DC flows in one direction, AC repeatedly changes direction.
What is the purpose of the earth wire in a plug?
It stops the appliance becoming live by carrying current only if there’s a fault.
What does the live wire do?
Carries high potential difference (230 V) from the mains; dangerous if touched.
What is the purpose of the fuse in a plug?
It melts and breaks the circuit if the current is too high, preventing danger.
Why is plastic used in plug casings?
Plastic is a good electrical insulator.
What does the neutral wire do?
Completes the circuit with a potential difference of 0 V.
What does the National Grid do?
Transfers electricity from power stations to homes and businesses.
Why are step-up transformers used?
To increase potential difference and reduce current, minimizing energy loss.
Why are step-down transformers used?
To reduce potential difference to a safe level for homes (230 V).
How is power calculated using current and voltage?
P = IV
How is power loss due to resistance calculated?
P = I²R
Why is high voltage used in transmission?
It reduces current, which decreases energy lost as heat.
How do you calculate charge flow?
Q = I × t
How do you calculate energy transferred?
E = Q × V
How do you calculate power using energy and time?
P = E ÷ t
