🔍 Unit 4: Wave Nature of Light — Mid-Unit Diagnostic
Assessment FOR Learning
📋 Not Graded — Teacher Feedback Only
Purpose: Diagnose readiness for the wave-optics unit. Prerequisites: SPH3U wave properties (\(v=f\lambda\), reflection, refraction, simple ray diagrams), trigonometry, scientific notation. Be honest — this guides instruction.
Section A — Prerequisites (Knowledge & Understanding)
Q1 — Wave equation [3]
A water wave has wavelength \(0.40\,\text{m}\) and period \(0.50\,\text{s}\). Find the speed and frequency.
Q2 — Reflection & refraction (SPH3U) [3]
State the law of reflection and Snell's law. For light entering a denser medium, does it bend toward or away from the normal? Why?
Q3 — Trigonometry quick-check [2]
Compute (a) \(\sin 30°\), (b) \(\cos 60°\), (c) \(\tan 45°\), and (d) \(\sin^{-1}(0.5)\) in degrees.
Section B — Bridge to New Concepts (Thinking)
Q4 — Two-source interference (concept) [4]
Two in-phase sources of identical wavelength produce overlapping waves. (a) State the path-difference condition for constructive interference. (b) State the condition for destructive interference. (c) Predict whether \(\Delta y\) (fringe spacing) increases or decreases when slit separation \(d\) decreases.
Q5 — Diffraction limit estimate [4]
Visible light has \(\lambda \sim 5\times10^{-7}\,\text{m}\). Estimate, qualitatively, the slit width below which significant diffraction begins, and explain why we don't notice diffraction of light around everyday objects (windows, doorways).
Section C — Reflection (Communication)
Q6 — What's hardest? [2]
Which topic in Unit 4 do you find most challenging so far (refraction, double-slit, single-slit, thin films, polarization)? What specific step or concept trips you up?