WBJEE · Physics · Wave Optics
A thin plastic sheet of refractive index 1.6 is used to cover one of the slits of a clouble slit arrangement. The central point on the scireen is now occupied by what would have been the 7th bright fringo before the plastic was used. If the wavelength of light is \(600 \mathrm{nm}\), what is the thickness (in \(\mu \mathrm{m}\) ) of the plastic sheet?
- A 7
- B 4
- C 8
- D 6
Answer & Solution
Correct Answer
(A) 7
Step-by-step Solution
Detailed explanation
The change in path length \(=(\mu-1) t\) This path length change the position of bright fringe upto seventh bright fringe. The thickness of plastic substance inserted in the path of rays will must be 7 (on assuming fringe width to be units).
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