Why does an excessively thin film appear black in reflected light ?
Text Solution
Verified by Experts
When `t lt lt lambda`, path difference in ligth reflected from two surfaces of thin film `= 2 mut cos r + lambda//2` reduces to `lambda//2`, which is the condition for destructive interference. Hence the film appears black.
Topper's Solved these Questions
OPTICS
PRADEEP|Exercise Very short answer question|5 Videos
OPTICS
PRADEEP|Exercise very short answer questions|1 Videos
Assertion: An excessively thin film appear black in reflected light. Reason: The film absorbs all the radiations falling on it.
A light of wavelength 5890Å falls normally on a thin air film. The minimum thickness of the film such that the film appears dark in reflected light is
Statement -1: If an exceedingly thin soap film is seen in reflected light, it may appear dark Statement -2 : Three is a phase difference of pi from the rays reflected from front and rear faces of the film.
Why does chlorophyll appear red in reflected light and green in transmitted light? Explain the significance of these phenomena in terms of photosynthesis.
Assertion (A) : The flim which appears bright in reflected system will appear dark in the transmitted system and vice-versa. Reason (R ) : The condittions for film to appear bright of dark in the reflected light are just revese to those in the transmitted light
A parallel beam of sodium light of wavelength 6000 Å is incident on a thin glass plate of mu=1.5 , such that the angle of refraction in the plate is 60^(@) . The smallest thickness of the plate which will make it appear dark by reflected light is
Why does a black board appears black in colour ?
What is the minimum thickness of a thin film (mu=1.2) that results in constructive interference in the reflected light? If the film is illuminated with light whose wavelength in free space is lambda=500nm ?
