Newton's rings are observed normally in reflected light of wavelength 5000 Å . The diameter of the 10 th dark ring is 0.005 ~m . The radius of curvature of the lens is

Step-by-step solution

In Newton's ring experiment, diameter of n th dark ring, D_ n =2 n R = D_ n ² 4 n ...(i) Given, n=10, D₁₀=0.005 ~m =5000 Å=5 10⁻⁷ ~m Putting these values in Eq. (i), we get R= (0.005)² 4 10 5 10⁻⁷ =1.25 ~m