Question

In Fraunhofer diffraction experiment, $L$ is the distance between screen and the obstacle, $b$ is the size of obstacle and $A$ is wavelength of incident light. The general condition for the applicability of Fraunhofer diffraction is

• A. $\frac{b^2}{L\lambda }\gg 1$
• B. $\frac{b^2}{L\lambda }=1$
• C. $\frac{b^2}{L\lambda }\ll 1$
• D. $\frac{b^2}{L\lambda }\ne 1$

Answer 1

The correct option is C $\frac{b^2}{L\lambda }\ll 1$

The general condition for Froun hofer diffraction is $\frac{b^2}{L\lambda }\ll 1$