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 diffraction as a wave spreading through an opening or around an edge, and say that λ and f do not change. (Guide: “Waves bend around edges”)
- I can predict which of several gaps makes a wave spread most by comparing each width with λ. (Guide: Figure 1; Practice Q1, Q6a)
- I can explain why you hear around a corner but do not see around it. (Guide: “Gap size compared with wavelength”)
- I can explain that a single slit gives bands because wavelets from different parts of the slit interfere. (Guide: “Why a single slit gives bands”)
- I can describe how the shape of the opening changes the pattern, including a round hole. (Guide: “Shape of the opening”; Practice Q7d)
Calculation and skills
- I can show that the edge-to-edge path difference is a sin θ and explain why a path difference of λ gives a dark fringe. (Guide: Figure 2; Practice Q2)
- I can use a sin θ = mλ and y_min = mλL/a, and check that the small-angle form is valid. (Guide: Worked example 1; Practice Q4, Q5)
- I can find the widths of the central band and of a side band. (Practice Q5)
- I can find λ or a from measurements of a pattern, including a graph of y against m. (Guide: Worked example 2; Practice Q7)
Reasoning
- I can predict the factor by which the pattern changes when a, λ, f or L changes. (Guide: Worked example 2; Practice Q3, Q6d, Q7c)
- I can explain why there are no dark fringes when the gap is narrower than one wavelength. (Practice Q6c)
- I can tell the single-slit dark condition apart from the double-slit bright condition. (Guide: “Common misconceptions”; Practice Q4)
All ticked? Move on to Topic 14.8: Double-Slit Interference and Diffraction Gratings, or return to the course roadmap.