Question

For an aperture of size a illuminated by a parallel beam of light having wavelength $\lambda ,$ the Fresnel distance is

• A. $\approx a/\lambda$
• B. $\approx a^2/\lambda$
• C. $\approx a^2\lambda$
• D. $\approx a/{\lambda }^2$

Answer 1

Answer: (B)

In this case, the Fresnel distance is equavelent to $a^2/\lambda$