clc;
clear;
R=100 //radius of curvature in cm
D_5=0.3 //diameter of the 5th dark ring in cm
D_25=0.8 //diameter of the 25th dark ring in cm
n5=5 //fifth dark ring
n25=25 //twenty fifth ring

//calculation
p = n25 - n5 //difference in no of fringes
lambda=((D_25^2)-(D_5^2))/(4*p*R)

mprintf("The wavelength of light used is = %1.2e cm",lambda)
//The answer provided in the textbook is wrong.