Wave phenomena: reflection, refraction, diffraction and interference

Learning objectives

Apply the law of reflection and Snell's law n₁ sinθ₁ = n₂ sinθ₂, and relate refractive index to wave speed using n₁v₁ = n₂v₂ and n = c/v

Calculate the critical angle from sinθc = n₂/n₁, explain total internal reflection, and describe its use in optical fibres and reflecting prisms

Describe the diffraction of a wave at a single slit or an aperture, and explain why the spreading increases as the ratio of wavelength to slit width increases

Apply the principle of superposition to find the resultant displacement where waves overlap, and predict constructive or destructive interference from a path difference of a whole number of wavelengths or an odd number of half wavelengths

Apply s = λD/d to the fringe pattern of Young's double-slit experiment, and predict how the fringe spacing changes with slit separation, wavelength and slit-to-screen distance

(HL) Locate the first minimum of a single-slit diffraction pattern from θ = λ/b, describe how the single-slit envelope modulates a double-slit pattern, and apply the diffraction grating equation nλ = d sinθ to find wavelengths and orders