Electricity Amd Circuits Flashcards
(23 cards)
What do circuit diagrams show?
The arrangement of components using standard symbols.
How is a voltmeter connected in a circuit?
In parallel with the component.
What does potential difference measure?
The energy transferred per unit charge.
What is the unit of potential difference?
The volt (V).
What is the formula for energy transferred?
E = Q × V.
How is an ammeter connected in a circuit?
In series with the component.
What is electric current?
The rate of flow of charge.
What is the formula for charge?
Q = I × t.
What causes current in a circuit?
A source of potential difference in a closed circuit.
What happens to current at a junction?
It is conserved — the total current in equals the total current out.
What happens to current when resistance increases?
Current decreases if potential difference stays the same.
How can resistance be changed?
By using a variable resistor.
What is the formula for resistance?
V = I × R.
What happens to resistance in series?
It increases — total resistance is the sum of individual resistors.
What happens to resistance in parallel?
It decreases — more paths for current to flow.
How does current vary with voltage in a filament lamp?
As voltage increases, resistance increases, so current increases less.
What happens to resistance of an LDR with light intensity?
It decreases as light intensity increases.
What happens to resistance of a thermistor with temperature?
It decreases as temperature increases.
Why do resistors get hot?
Due to energy transferred by current doing work against resistance.
How can unwanted energy transfer be reduced in circuits?
By using low-resistance wires.
What is the formula for power?
P = E / t or P = I × V or P = I² × R.
What is the frequency and voltage of UK mains supply?
50 Hz and 230 V.
What is the function of the earth wire?
It provides a path for current to ground in case of a fault for safety.
