P4 - Electrical Circuits Flashcards
Potential difference / voltage
Work done per unit charge that passes between two points in an electrical circuit
Voltmeter
Voltage is measured in volts (V) using a voltmeter
A voltmeter must be connected in parallel of the component as it measures the p.d across the circuit
Voltage in a series circuit
The p.d is shared among components, with the same voltage for each component
Total V = V1 + V2
Voltage in a parallel circuit
The p.d supplied is equal to the voltages across each of the parallel components
V1 = V2 = V3
Current
The amount of charge that passes a specific point in the circuit
Ammeter
Current is measured in amperes (A) using an ammeter
An ammeter must be connected in series with the circuit to measure the current flowing through it
Current in a series circuit
The current flows through one continuous pathway, the current flowing through it
Current in a parallel circuit
The current divides at the point where the circuit branches
Resistance
Is the opposition to the flow of charge
Measured in ohms (Ω)
Resistance in a series circuit
When two or more resistors are connected, the combined resistance is higher than the individual resistance
Total R = R1 + R2
Resistance in a parallel circuit
When two or more resistors are connected, the current splits at the branches and does not go through each resistor, therefore the total combined resistance is less than any of the individual resistors
1 / total resistance = 1 / R1 + 1 / R2
Diode
Allows current to flow in a forward direction
The diode has a very high resistance in the reverse direction (current and voltage is never negative)
Light-dependent resistor (LDR)
The resistance of an LDR decreases as light intensity increases
Filament lamp
The resistance of a filament lamp increases as the temperature of the filament increases
Resistor
Resistance remains constant as the current changes
Current and voltage are directly proportional
