Figure 8 shows identical filament lamps connected together to a 12V power supply - Edexcel - GCSE Physics Combined Science - Question 6 - 2018 - Paper 1

To calculate the resistance of each lamp, we can use the formula relating power, voltage, and resistance:

$P = \frac{V^2}{R}$

Rearranging to find resistance gives:

$R = \frac{V^2}{P}$

Substituting the known values (Voltage = 1.5V and Power = 0.75W):

$R = \frac{(1.5)^2}{0.75} = \frac{2.25}{0.75} = 3\Omega$

Thus, the resistance of each lamp is 3Ω.

To investigate the relationship between the resistance of a lamp and the potential difference, a student could set up a circuit that includes:

1. A power supply (to provide varying potential differences).
2. An ammeter (to measure current through the lamp).
3. A voltmeter (to measure the potential difference across the lamp).
4. A single filament lamp.

Method:

• Connect the circuit as shown in the diagram.
• Gradually increase the potential difference using the power supply while measuring and recording the current from the ammeter and the voltage across the lamp from the voltmeter.
• For each recorded value of voltage and current, calculate the resistance using Ohm's Law:

$R = \frac{V}{I}$

• Repeat the measurements multiple times to ensure accuracy, and plot a graph of resistance against potential difference to analyze the results.