A thin film of a material of refractive index 1.38 is coated on a glass surface of refractive index 1.5.Light of wavelength 550 nm gives no reflected light. The minimum thickness of the film is :

A thin film of a material of refractive index 1.38 is coated on a glas

1.	A thin film of a material of refractive index 1.38 is coated on a glass surface of refractive index 1.5.Light of wavelength 550 nm gives no reflected light. The minimum thickness of the film is :
Answer» `500 dotA` `750 Å` `1000 Å` `1500 Å` SOLUTION :Since both the reflections take place at denser surfaces, the CONDITION for minima is `2nt = ( m + 1/2) lambda` or `t = ((m + 1/2)lambda)/(2n)` ` = (lambda)/(4N)(for m = 0) = (5500)/(4 xx 1.38) Å`

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A thin film of a material of refractive index 1.38 is coated on a glass surface of refractive index 1.5.Light of wavelength 550 nm gives no reflected light. The minimum thickness of the film is :

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