Bright and Dark Fringes Are Seen on a Screen When $d = \frac { \lambda _ { \text {air } } } { 2 }$

question 55

Multiple Choice

Bright and dark fringes are seen on a screen when light from a single source reaches two narrow slits a short distance apart.Each bright fringe will shift to the location of the adjacent bright fringe if a thin film is placed in front of one of the slits.The minimum thickness of this film must be

• A) \(d = \frac { \lambda _ { \text {air } } } { 2 }\) .
• B) \(d = \frac { \lambda _ { \text {oir } } } { 2 n _ { \text {film } } }\) .
• C) \(d = \frac { \lambda _ { \text {oir } } } { \left( n _ { film } - 1 \right) }\) .
• D) \(d = \frac { \lambda _ { \text {air } } } { 2 \left( n _ { film } - 1 \right) }\) .
• E) \(d = \frac { \lambda _ { \text {air } } } { n _ { \text {film } } }\) .

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