alleryFor maximum brightness in Newton's rings (reflected light, air film), what is the radius of n-th bright ring? (R = lens radius, λ = wavelength)
Asqrt(nλR)
Bsqrt((2n+1)λR/2)
Csqrt(nλR/2)
Dsqrt(nλ/R)
Answer & Solution
Correct answer: B. sqrt((2n+1)λR/2)
In Newton's rings (reflected light), there is a phase change at the lower glass surface but not at the upper.
**For bright ring:** 2t = (n + 1/2)λ where t = r²/(2R).
**So r_n = sqrt((2n+1)λR/2).**
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