ELECTRICAL CIRCUITS P2 5.1
Every component has its own symbol. Theses components are connected to form circuits. A circuit diagram shows this circuit.
RESSISTANCE P2 5.2/5.3
Current potential graphs are used to show how the current passing through a component varies with the potential different across it.
The current is measured with an ammeter. The potential difference is measured with an voltmeter.
The current through a resistor at a constant temperature is directly proportional to the potential difference cross the resistor.
Resistance (ohms) = Potential difference (V) / Current (A)
Below current potential difference graphs for a diode and a filament lamp.
SERIES CIRCUITS P2 5.4
If current connected in series components are connected one after the other so a break would stop the flow of charge.
current = potential difference / total ressistance or
Potential difference = current x resistance
This can be used to find the individual potential difference of each component.
For components in a series
- The current is the same in each component
- The potential differences add to give the total potential difference
- The resistances add to give the total resistance
- The bigger the ressistance of a components the bigger its share of potential difference
PARALLEL CIRCUITS P2 5.5
In a parallel circuit each component is connected across the supply, so if there is a break in the circuit the charge supply still continues.
For components in parallel:
- The potential difference is the same across each component.
- The total current is the sum of the currents through each component
- The bigger the ressistance of a component, the smaller its current is.