Estimate the Distance for Which Ray Optics is Good Approximation for an Aperture of 4 Mm and Wavelength 400 Nm. - Physics

Estimate the distance for which ray optics is good approximation for an aperture of 4 mm and wavelength 400 nm.

Solution

Fresnel’s distance (ZF) is the distance for which the ray optics is a good approximation. It is given by the relation,

Z_r = a^2/lambda

Where,

Aperture width, a = 4 mm = 4 ×10−3 m

Wavelength of light, λ = 400 nm = 400 × 10−9 m

Z_r = (4xx10^(-3))^2/(400 xx 10^(-9)) = 40 m

Therefore, the distance for which the ray optics is a good approximation is 40 m.

Concept: Diffraction - The Single Slit
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APPEARS IN

NCERT Class 12 Physics Textbook
Chapter 10 Wave Optics
Q 10 | Page 383