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#optics physics

2 public questions tagged with this topic.

Polarization and Malus Law

Why does light exhibit polarization only in specific directions when passing through a polaroid?

**Two polaroids** with pass-axes perpendicular intensity zero because second blocks component, with 45° intensity I₀/4 if initial after first I₀, if initial unpolarized I₀, after first I₀/2 then after second at 45° I₀/4. Three polaroids first and third crossed 90°, middle at 45° maximum transmission because middle rotates polarization, I after first I₀/2, after middle at 45° I₀/4, after third at 45° to middle I₀/4×cos²45°= I₀/8, non-zero, maximum when middle 45°. The polaroid aligns the electric field along its pass-axis, absorbing components in other directions, restricting polarization to th

Ref: NCERT > Physics Book > Wave Optics > Polarization and Malus Law

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Diffraction - Single-Slit and Central Maximum

What property of light waves causes the bending of rays around corners in a diffraction experiment?

**Single-slit diffraction** central maximum width W =2λ D/a, a slit width, D distance, angular width θ =2λ/a, first minimum at a sinθ = λ, fourth minimum a sinθ=4λ, sinθ=4λ/a, for a=5.0 μm λ=500 nm sinθ=4×0.5/5=0.4 θ≈23.6°, central maximum width increases when slit width reduced to half doubles width, when wavelength quadrupled width quadruples, when slit tripled width one-third. Light’s wave nature allows it to spread and bend around obstacles when encountering apertures comparable to its wavelength, unlike particle-like straight paths. Using Δ = d sinθ, y = n λ D/d, a sinθ = n λ, I = I₀ cos²

Ref: NCERT > Physics Book > Wave Optics > Diffraction - Single-Slit and Central Maximum

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