Question
Download Solution PDFWhite light reflected from a soap film (Refractive Index = 1.5) has a maxima at 600 nm and a minima at 750 nm with no minimum in between. Then the thickness of the film is ______ × 10-7 m.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFCONCEPT:
- Interference: A phenomenon in which two waves superpose on each other to form a resultant wave of greater, lower, or the same amplitude is called interference.
- Thin-film interference: When light waves reflecting off from the top and bottom surfaces of a thin film interfere with another
Due to interference in Thin Films, there occurs maxima and minima.
For maxima:
for minima:
where μ is the refractive index of thin film, t is the thickness of soap film, r is the angle of reflection, n is the nth fringe, and λ is the wavelength.
CALCULATION:
Given that
λ1 = 600nm;
λ2 = 750 nm;
μ = 1.5
For maxima
for minima
divide eq (i) and eq (ii)
n = 2
put in eq (ii)
t = 500 nm = 5 × 10-7
so the correct answer is option 3.
Last updated on Jul 16, 2025
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