clc 
// Given that
l = 1e-10 //length of box in m
e = 1.6e-19 // charge on an electron in C
m = 9.1e-31 // mass of electron in kg
h = 6.62e-34 // Planck constant in J-sec
// Sample Problem 10 on page no. 16.18
printf("\n # PROBLEM 10 # \n")
printf("Standard formula used \n")
printf("E = (n^2 * h^2) / (8 * m * l^2) \n")
n = 1 // for n=1
E = (n^2 * h^2) / (8 * m * l^2)
n = 2 // for n=2
E_ = (n^2 * h^2) / (8 * m * l^2)
d = (E_ - E) * (1 / e)
printf("\n Energy difference is %f eV.",d)