Overview
This lecture explains what potential difference (voltage) is, how it is measured, and how it behaves in series circuits using simple examples.
What is Potential Difference?
- Potential difference (voltage) is the amount of energy transferred per coulomb of charge in a circuit.
- It is measured in volts (V).
- One volt means one joule of energy is transferred for each coulomb of charge.
- Potential difference indicates how energy is transferred from the cell to components in the circuit.
Measuring Potential Difference
- A voltmeter is used to measure potential difference.
- The voltmeter must be placed across (in parallel with) the component being measured.
- The circuit symbol for the voltmeter should be learned.
Potential Difference in Series Circuits
- In a simple circuit with one lamp and a cell providing 9V, the lamp receives all 9V, making it bright.
- In a series circuit with two identical lamps and the same 9V cell, the potential difference is shared; each lamp receives 4.5V and both are dimmer.
- If the lamps are different, they can receive different voltages (e.g., 6V and 3V), but the total potential difference across both lamps equals the cell’s voltage.
- The lamp with a higher potential difference will be brighter, as it transfers more energy.
Key Terms & Definitions
- Potential Difference (Voltage) — Energy transferred per coulomb of charge, measured in volts (V).
- Volt (V) — SI unit for potential difference, equivalent to one joule per coulomb.
- Voltmeter — Instrument used to measure the potential difference across components.
Action Items / Next Steps
- Practice questions on potential difference in series circuits in the revision workbook.
- Learn and memorize the voltmeter circuit symbol.