Wave Phenomena (Reflection, Refraction, Diffraction, Interference) — A/L Physics

What must I remember about Wave Phenomena (Reflection, Refraction, Diffraction, Interference)?

• Reflection & Refraction: Reflection: Angle of incidence equals angle of reflection; Refraction: Snell's Law n1 sin θ1 = n2 sin θ2; Frequency f remains invariant across interface, whereas wavelength λ and speed v change (v1/v2 = λ1/λ2 = n2/n1).
• Total Internal Reflection (TIR): Occurs when light travels from denser to rarer medium at incident angle exceeding critical angle: sin C = n_rare / n_dense = 1 / n; exploited in optical fibers and prisms.
• Diffraction: Bending of wavefronts around obstacles or apertures; pronounced when aperture size 'a' is comparable to wavelength λ (a ≈ λ); diffraction angle for central maximum sin θ = λ / a.
• Interference & Coherence: Superposition of two coherent wave sources (constant phase relationship): Constructive interference occurs when path difference Δx = n λ (phase difference Δφ = 2nπ); Destructive interference occurs when Δx = (n + 1/2)λ (Δφ = (2n + 1)π).

Test yourself (1 minute)

1. Young's Double Slit Formula

   Fringe width β = (λ D) / d, where D is screen distance and d is slit separation; fringe width increases with longer wavelength (red > blue) and larger screen distance.

2. Diffraction Grating Equation

   d sin θ = n λ, where d is grating element (d = 1 / N lines per meter) and n is spectral order (n = 0, 1, 2, ...); maximum observable order n_max ≤ d / λ.

3. Conditions for Sustained Interference

   Sources must be coherent, monochromatic, have equal/comparable amplitudes, and be positioned close together with small path differences.

Practise Wave Phenomena (Reflection, Refraction, Diffraction, Interference) questions today

Source: NIE G.C.E. (A/L) Physics Resource Book - Unit 3: Waves & Light

What should I study first?

What comes next?

Next in the syllabus

Where does Wave Phenomena (Reflection, Refraction, Diffraction, Interference) fit in the syllabus?

Unit 3.3 · Year 1 · Term 2