MCQ
A very thin film in reflected white light appears:
- Acoloured
- Bwhite
- ✓black
- Dred
✓
Answer
Correct option: C.
black
For very thin films the distance travelled inside the film is insignificant and so the two reflected waves are almost exactly out of phase with each other $($due to the phase change at one surface$)$; they interfere destructively and the film appears 'black'.
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