JEE MAIN - Physics (2025 - 22nd January Evening Shift - No. 14)
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.]
68.7 nm
137.5 nm
94.8 nm
275 nm
Explanation
_22nd_January_Evening_Shift_en_14_1.png)
For transmitted green light to be maxima, reflected green should be minima.
$$\begin{aligned} & \Delta \mathrm{P}=2 \mu_0 \mathrm{t}=\mathrm{n} \lambda \\ & \Rightarrow \mathrm{t}=\frac{\mathrm{n} \lambda}{2 \mu_0} \therefore \mathrm{t}_{\min }=\frac{\lambda}{2 \mu_0}=\frac{550}{2 \times 2}=137.5 \end{aligned}$$
Comments (0)
