For Newton's ring, prove that diameters of nth dark ring is directly proportional to the square root of natural number.

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written 6.2 years ago by

vermavarsha432 • 1.0k

modified 4.9 years ago by

sanketshingote • 100

In Newton's ring experiment the diameter of n th and (n+8) bright rings are 4.2mm and 7mm respectively. Radius of curvature of lower surface of lens is 2m. Determine the wavelength of light used.

advanced engineering physics

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written 6.1 years ago by

vermavarsha432 • 1.0k

modified 6.0 years ago by

yashbeer ★ 11k

Let POQ be the plano-convex lens placed on a plane glass plate AB. Let R be the radius of curvature of the lens surface in contact with the plate.

Let p be the radius of a Newton's ring corresponding to the constant film thickness 't'. The path difference between the two interfering rays in the reflected system is

$2\mu \ cos(r + \theta) + \frac{\lambda}{2}$

$\lambda =$ Wavelength of incident light

$\mu = 1$ for air film

$r = 0$ for normal incidence

$\theta = 0$ for large R

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