Question

If one of the slits of a standard Young's double slit experiment is covered by a thin parallel sided glass slab so that it transmits only one half the light intensity of the other, then :

• A. The fringe pattern will get shifted towards the covered slit
• B. The fringe pattern will get shifted away from the covered slit
• C. The bright fringes will become less bright and the dark ones will becomes more bright
• D. The fringe width will remain unchanged

Answer 1

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

Glass slab introduces extra path difference o fringe pattern will get shifted towards covered slit. Due to reduced intensity of one of the slits, intensity of bright fringe decreases and that of dark fringe increases. Fringe width is given as
$\beta=\frac{\lambda D}{d}$
Hence fringe width will remain constant.