C.3 Wave phenomena

• Waves travelling in two and three dimensions can be described through the concepts of wavefronts and rays.

• Snell’s law: n1 sinθ1 = n2 sinθ2.

• Refractive index: n=c/v.

• Total internal reflection condition uses critical angle: sinθc=n2/n1.

• Superposition adds displacements where waves overlap.

• Coherence requires constant phase difference between waves.

• Path difference determines constructive or destructive interference.

• Two-source interference depends on path difference and wavelength.

• Young double-slit spacing: s = λD/d.

• Thin-film interference arises from reflected waves and phase changes.

• Resolution is limited by diffraction; Rayleigh criterion sets resolvability.