Question : When a film is illuminated by white light, its upper portion appears dark. Path difference between two reflected beams at the spot must be
A. zero
B. λ/2
C. 2 λ/2
D. π
Answer:B
Question : When a film is illuminated by white light, its upper portion appears dark. Path difference between two reflected beams at the spot must be
A. zero B. λ/2 C. 2 λ/2 D. π