Electricity Flashcards
What is the unit of charge?
Coulombs (c)
Define electric current.
The flow of electrons (or charge) in a circuit.
What is the unit of current?
Amperes (A)
How does resistance affect current?
Higher resistance reduces current.
What happens to the resistance of a filament lamp as temperature increases?
It increases because ions vibrate more, making it harder for electrons to flow.
What is the function of a diode?
Allows current to flow in one direction only.
How does a LDR (Light-Dependent Resistor) work?
Resistance decreases as light intensity increases.
How does a thermistor work?
Resistance decreases as temperature increases.
What happens to current in a series circuit?
It is the same at all points.
What happens to voltage in a parallel circuit?
It is the same across each branch.
What does the National Grid do?
Transfers electricity from power stations to homes and businesses.
Why are transformers used in the National Grid?
To increase voltage and reduce current, minimizing energy loss as heat.
What is the function of a step-up transformer?
Increases voltage and decreases current for efficient transmission.
What is the function of a step-down transformer?
Decreases voltage for safe use in homes (230V in the UK).
What are the three wires in a plug and their functions?
• Live wire (brown): Carries current to the appliance.
• Neutral wire (blue): Completes the circuit.
• Earth wire (green/yellow): Prevents electric shocks by grounding excess current.
Why are fuses used in plugs?
To break the circuit if current is too high, preventing fires and damage.
What is the function of a circuit breaker?
Cuts off power faster than a fuse when a fault occurs.
