A transparent film of refractive index, 2.0 is coated on a glass...

A transparent film of refractive index, 2.0 is coated on a glass slab of refractive index, 1.45. What is the minimum thickness of transparent film to be coated for the maximum transmission of Green light of wavelength 550 nm . [Assume that the light is incident nearly perpendicular to the glass surface.] $A transparent film of refractive index, 2.0 is coated on a glass slab of refractive index, 1.45. What is the minimum$

Options

A137.5 nm
B275 nm
C94.8 nm
D68.7 nm

Correct answer

A. 137.5 nm

Step-by-step solution

$A transparent film of refractive index, 2.0 is coated on a glass slab of refractive index, 1.45. What is the minimum$
For transmitted green light to be maxima, reflected green should be minima.

\begin{aligned} & \Delta \mathrm{P}=2 \mu_0 \mathrm{t}=\mathrm{n} \lambda \\ & \Rightarrow \mathrm{t}=\frac{\mathrm{n} \lambda}{2 \mu_0} \therefore \mathrm{t}_{\min }=\frac{\lambda}{2 \mu_0}=\frac{550}{2 \times 2}=137.5 \end{aligned}

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