A glass surface is coated by an oil film of uniform thickness 1.00 × 10-4 cm. The index of refraction of the oil is 1.25 and that of the glass is 1.50. Find the wavelengths of light in the visible region (400 nm-750 nm) which are completely transmitted by the oil film under normal incidence.
Shane Macguire , 11 Years ago
Grade upto college level
1 Answers
Deepak Patra
Last Activity: 11 Years ago
Sol. Given that, λ = 560 * 10^–9 m, μ = 1.4.
For strong reflection, 2μd = (2n + 1)λ/2 ⇒ d = (2n + 1)λ/4d
For minimum thickness, putting n = 0.
⇒ d = λ/4d ⇒ d = 560 * 10^-9/14 = 10^-7 m = 100 nm.
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