4.2.4.1 Power

Spec reference: 4.2.4 (subtopic).

What you need to know

• power pack and ammeter in series and the voltmeter
• across the power pack.
• 5. Using the pipette, put a drop of water into the small hole.
• 6. Put the thermometer into the small hole and measure the
• temperature.
• 7. Switch the power pack to 12V and turn it on.
• 8. Read and record the voltmeter and ammeter readings – during
• the experiment, they shouldn’t change.

Self-assessment (checklist)

• I can explain how the power transfer in a circuit device
• I can recall and apply the equation linking current,
• I can rearrange the equation linking current, potential
• I can recall and apply the equation linking current, power
• I can rearrange the equation linking current, power and

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.