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 state Gauss’s law, Φ_E = ∮E·dA = q_enc/ε₀, and explain each symbol, including the outward area vector. (Guide: “From flux to Gauss’s law”)
- I can explain why the flux through a closed surface does not depend on its size when q_enc is fixed. (Guide: “From flux to Gauss’s law”; Practice Q1)
- I can explain why zero net flux does not mean zero field on the surface. (Guide: “Common misconceptions”)
- I can say when Gauss’s law is useful for finding E and when it is true but not helpful. (Guide: “Choosing a Gaussian surface”)
Calculation and skills
- I can choose a spherical, cylindrical or pillbox Gaussian surface and justify the choice from the symmetry. (Practice Q5, Q6)
- I can derive E inside and outside a uniformly charged sphere and evaluate it with numbers. (Guide: Worked example 1)
- I can derive the field of an infinite line and of an infinite sheet. (Guide: “Standard results”; Practice Q2, Q5)
- I can find the net enclosed charge when several charges lie at different radii. (Practice Q4)
- I can set up and evaluate q_enc = ∫ρ(r′)4πr′² dr′ for a non-uniform density. (Guide: Worked example 2; Practice Q7)
- I can sketch E(r) for a sphere or cylinder and label the value at the surface. (Guide: Figure 1; Practice Q6)
Reasoning
- I can check a result for continuity at r = R and for point-charge behaviour at large r. (Guide: Worked example 2; Practice Q6, Q7)
- I can predict a factor of change in E, such as E(R/2)/E(R), from the functional dependence. (Practice Q3)
- I can find where the field is greatest by setting dE/dr = 0. (Practice Q7)
All ticked? You have finished this unit. Move on to Unit 9, Electric Potential, starting with Topic 9.1, Electric Potential Energy, or return to the course roadmap.