Wave Optics

Interference, Diffraction, Polarization

Interference, diffraction, and polarization can only be explained by wave nature of light. The photoelectric effect requires particle nature of light (photons) for explanation.

Half the original

When unpolarized light passes through a polarizer, the intensity is reduced to half because only one component of the electric field vector passes through.

λ

For single slit diffraction, the first minimum occurs when a sin θ = λ, where 'a' is the slit width. This allows pairing of rays with λ/2 path difference for destructive interference.

Same frequency, Constant phase difference

Coherent sources must have the same frequency and a constant phase difference. Same amplitude and polarization are desirable but not essential for coherence.