Why does light exhibit both interference and diffraction despite traveling in straight lines in everyday observations?
**Single-slit pattern** intensity I = I₀ (sinα/α)², α=π a sinθ/λ, central maximum at α=0, minima at α=nπ, so a sinθ=nλ, width increases with λ and D decreases with a, for a=15 μm λ=750 nm first minimum sinθ=750/15000=0.05 θ≈2.87°, angular width of central maximum 2θ≈5.74°. Light’s wavelength is very small compared to typical objects, making straight-line behavior dominant, but wave effects like interference and diffraction emerge with small apertures. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ, n = c/v, sinC = 1/n, λ' = λ/n and A = 2a cos(φ/2), calculation gives Small wavelength
Ref: NCERT > Physics Book > Wave Optics > Diffraction - Single-Slit and Central Maximum
