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 describe a capacitor as two separated conductors with charges +Q and −Q, and explain why its net charge is zero. (Guide: “What a capacitor is”)
- I can define capacitance as C = Q/ΔV and explain why it depends only on shape, size and gap material. (Guide: “What a capacitor is”; Practice Q1)
- I can explain why the field between parallel plates is uniform, except near the edges, and nearly zero outside. (Guide: Figure 1)
- I can explain why the stored energy is ½QΔV and not QΔV. (Guide: “Energy stored in a capacitor”; Practice Q7)
Calculation and skills
- I can use Gauss’s law and superposition to show that E = σ/ε₀ between parallel plates. (Guide: “The parallel-plate capacitor”)
- I can calculate C, Q, E and U for a parallel-plate capacitor with units. (Guide: Worked example 1; Practice Q4)
- I can derive the capacitance of a concentric spherical capacitor and of a coaxial cylindrical capacitor. (Guide: Worked example 2; Practice Q3, Q6)
- I can derive U = Q²/(2C) by integrating (q/C) dq, and sketch ΔV against q. (Guide: Figure 2; Practice Q7)
- I can find the deflection of a charged particle between plates using constant-acceleration equations. (Guide: Worked example 3; Practice Q5)
Reasoning
- I can decide whether Q or ΔV stays fixed and predict how C, ΔV, E and U change when the plate separation changes. (Guide: “Fixed charge or fixed potential difference?”; Practice Q2, Q4)
- I can check a capacitance formula with limiting cases, such as b → ∞ or a thin gap. (Guide: “A method for any capacitor”; Practice Q6)
- I can explain where the energy comes from when an isolated capacitor’s plates are pulled apart. (Guide: Worked example 1; Practice Q7)
All ticked? Move on to Topic 10.4, Dielectrics, or return to the course roadmap.