Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can derive P = IΔV from dU = ΔV dq and I = dq/dt, and show that 1 V·A = 1 W. (Guide: “Where electric power comes from”)
- I can say which elements deliver energy to a circuit and which receive it, and use energy conservation as a check. (Guide: “Sources and receivers of energy”; Worked example 1)
- I can explain that a bulb’s brightness increases with the power it receives. (Guide: “Predicting the brightness of bulbs”; Practice Q3)
- I can explain that a resistor dissipates electrical energy as thermal energy at the rate I²R. (Guide: “Power in a resistor: three forms”; Practice Q5)
Calculation and skills
- I can calculate power using P = IΔV, I²R or ΔV²/R, choosing the most suitable form. (Practice Q1, Q5)
- I can find a resistance from a power rating, or a safe maximum ΔV or I. (Practice Q3, Q5)
- I can find the energy transferred when power changes with time, using E = ∫P dt. (Guide: Worked example 3; Practice Q6)
- I can draw a power bar chart or sketch a P–t graph and explain what its area means. (Guide: Figures 2 and 3; Practice Q6)
- I can convert between joules and kilowatt-hours. (Guide: “A note on units of energy”; Practice Q7)
Reasoning
- I can predict how power changes when R or ΔV changes, stating what is held fixed. (Practice Q2)
- I can compare the brightness of two bulbs in series and in parallel, and explain why the order can swap. (Guide: Worked example 1; Practice Q7)
- I can account for the energy into a motor or generator as mechanical power plus thermal dissipation. (Guide: Worked example 2; Practice Q4)
- I can explain why squaring an average current gives the wrong energy. (Guide: Worked example 3; Practice Q6)
All ticked? Move on to Topic 11.5, Compound Direct Current Circuits, or return to the course roadmap.