4.2.1.3 Difference

Spec reference: 4.2.1 (subtopic).

What you need to know

• difference/volts (V).
• Dependent variable: current (A).
• Control variable: number of components (e.g. 1 filament
• bulb, 1 resistor), type of power source.
• Set up the circuits as shown below and measure the
• current and the potential difference.
• Draw graphs of the results once collected.
• Equations and Maths

Self-assessment (checklist)

• I can describe how the resistance and potential difference
• I can recall and apply the correct equation to calculate the
• I can rearrange the equation linking current, potential
• I can use circuit diagrams to set up and check appropriate

Key steps (method)

• Identify what the question is testing and use the correct equation/definition.
• Show substitutions and units clearly.

Common mistakes

• Unit conversions, rearranging errors, or quoting a law without applying it.