Practice question

**Frequency of light** remains unchanged when refracts from air into water because frequency determined by source, energy E= h f conserved, speed decreases v= c/n, wavelength decreases λ'=v/f= λ/n, energy of wave proportional to amplitude² not speed, intensity I =½ c ε₀ E₀², energy not depend on speed directly, when speed decreases amplitude may change but energy conserved, interference redistributes energy, total energy same, bright regions gain from dark. Large slit separation reduces the overlap of wavefronts, disrupting the consistent path difference needed for stable interference. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²θ,