Potential Difference
Physics: IB Diploma Higher Level, topic 4.5.5
Potential Difference
Potential difference is the difference in the amount of energy that charge carriers have between two points in a circuit.
Measured in volts
- Potential difference (p.d.) is measured in volts (V) and is also called voltage.
- The energy is transferred to the electrical components in a circuit when the charge carriers pass through them.
- We use a voltmeter to measure potential difference (or voltage).
Measurements in Circuits
Several different properties of currents can be measured.
Ammeters
- An ammeter measures the flow of current that passes through it.
- Ammeters have to be connected in series (in the same loop of the circuit) with the electrical component whose current you are measuring. For example component X above.
Voltmeters
- Voltmeters measure the potential difference (voltage) between two points in a circuit. For example between two points either side of component X above.
- Voltmeters must always be connected in parallel (on a separate branch of the circuit) with the two points being measured.
Current vs potential difference
- The current is a flow of charge. Current is measured through a component.
- Potential difference is the energy used between two points in a circuit, therefore it is measured between two points either side of a component.
- We describe this as the potential difference measured across a component.
Test yourself on Potential Difference
What instrument do you use to measure a potential difference?
Which of the following are true of potential difference?
What instrument is used to measure current?
Which of the following are true of measurements of a circuit?