Question

A thick rod D and sources $S_1$ and $S_2$ are some distance away from screen. $A_0$ and $B_0$ are region of shadow of sources $S_1$ and $S_2$. Both sources are monochromatic and coherent, then

• A. if sources move, half-shadows casted by them can remain in contact
• B. if sources move, half-shadows casted by them will converge or diverge
• C. if sources move, half-shadows casted by them may converge or diverge
• D. we may get fringe pattern on screen

Answer 1

Answer: (A), (C), (D)

The correct options are
A if sources move, half-shadows casted by them can remain in contact
C if sources move, half-shadows casted by them may converge or diverge
D we may get fringe pattern on screen

1. If source $S_1$ and $S_2$ move along tangents $S_{1}O$ and $S_{2}O$ their half shadows remain in contact.
2. If motion of $S_1$ and $S_2$ is not along $S_{1}O$ and $S_{2}O$ respectively, their shadows converge or diverge.
3. In the places where there is no shadow, fringe pattern can be expected.