Question

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

Answer 1

GIVEN ;-

⇒ Wavelength = 400 nm = 400 × 10 ⁻⁹

⇒Aperture      = 4 mm    =  4 ×10 ⁻³


TO FIND ;-

⇒ Fresnel''s  distance = ?


SOL ;-


⇒ Fresnel''s distance =  Aperture /  Wavelength


                               = 4 × 10⁻³       /    400 × 10⁻⁹

                               = 40 m


40 is the Fresnel '' s distance .

Answer 2

Answer:

Explanation:GIVEN ;-

⇒ Wavelength = 400 nm = 400 × 10 ⁻⁹

⇒Aperture = 4 mm = 4 ×10 ⁻³

TO FIND ;-

⇒ Fresnel''s distance = ?

SOL ;-

⇒ Fresnel''s distance = Aperture / Wavelength

= 4 × 10⁻³ / 400 × 10⁻⁹

= 40 m

40 is the Fresnel '' s distance .