As shown in the right figure, a point light source is placed at distance 2f from a lens with focus length f. and a screen is placed at 4f from the lens. The lens is then cut at the middle into two equal portions: upper half and lower half. the upper half is moved upwards by a small distance d comparable to the light wavelength and the lower half is moved downwards by the same distance d. What is the light pattern on the screen?

Options

A. Bright and dark stripes similar to the apttern seen in young's double slit experiment
B. bright and dark concentric rings
C. two large, bright and partly overlapping patches
D. two separate bright spots

Answer

A