1) Yellow light is incident on a single-slit 0.0315 mm wide. On a screen 70.0 cm away, a dark band appears 13.0 mm from the centre of the bright central band. Calculate the wavelength of the light.

Answer 1

tanφ = x/L =13•10^-3/0.7 =1.86•10^-2 ,
φ = 1.06º => sin φ =1.86•10^-2.
b•sin φ = k•λ,
λ = b•sin φ/k =0.0315•10^-3•1.86•10^-2/1 =5.85•10^-7 m