Concept explainers
(a)
The minimum thickness of coating needed to cancel visible light of wavelength
Answer to Problem 100QAP
The intensity of polarized light that passes through the stack of polarizing sheets is
Explanation of Solution
Given:
Refractive index for coating =
Refractive index for solar cell panel =
Formula used:
Formula for destructive interference due to thin film,
Calculation:
Since, path of light wave on the top and bottom face of the film changes by
So, reflected waves would be in phase. So, path difference between top and bottom surface of the film would be as,
Conclusion:
Thus, the minimum thickness of coating that cancel visible light of wavelength
(b)
The wavelength of visible light that cancel and reinforce the reflected light when thickness is increases by three times to its initial value
Answer to Problem 100QAP
The wavelength of the reflected light that cancels in air is
Explanation of Solution
Given:
Thickness of coating =
Refractive index for coating =
Refractive index for solar cell panel =
Formula used:
Formula for destructive interference due to thin film,
Calculation:
For destructive interference,
As we increase m, wavelength would be less than 240nm.
So, there is only one reflected wavelength lies in visible region that cancels is
Now, for constructive interference,
Conclusion:
Thus, the wavelength of reflected light that cancels is
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Chapter 23 Solutions
COLLEGE PHYSICS
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