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 explain why a double-slit pattern needs both diffraction and interference. (Guide: “Two slits, one light source”)
- I can explain why Young’s double-slit result is evidence that light behaves as a wave. (Guide: “Two slits, one light source”; Practice Q1)
- I can describe a real double-slit pattern as fringes inside a single-slit envelope, and explain a missing fringe. (Guide: Figure 2; Practice Q7c)
- I can explain why a grating gives sharper, brighter maxima than two slits with the same d. (Guide: “Diffraction gratings”; Practice Q7e)
- I can describe the white-light pattern from a grating: white centre, red farthest out in each order. (Guide: Figure 3; Practice Q4)
Calculation and skills
- I can show that the path difference is d sin θ and use it to say whether a point is bright or dark. (Guide: Figure 1; Practice Q2)
- I can use y_max = mλL/d to find fringe positions, spacing or d, and check the small-angle condition. (Guide: Worked example 1; Practice Q6, Q7a)
- I can find d from lines per millimetre and use d sin θ = mλ with tan θ = y/L at large angles. (Guide: Worked example 2; Practice Q5)
- I can find the highest order a grating produces. (Practice Q5d)
- I can plan a measurement of d or λ and analyse it with a straight-line graph. (Guide: “Planning a measurement”; Practice Q6)
Reasoning
- I can predict the factor by which the fringe spacing changes when λ, L or d changes. (Practice Q3)
- I can predict what happens to the pattern when one slit is covered. (Practice Q7d)
- I can decide whether two grating orders overlap. (Guide: Worked example 2)
All ticked? Move on to Topic 14.9: Thin-Film Interference, or return to the course roadmap.