 # PROBLEM 20 # 
Standard formula used 
 E = (n^2 * h^2) / (8 * m * L^2)) 
 p_n = n*h/(2*pi) 

 Energy Eigen value of electron -
 For (n=1) is 6.019835e-18 J.
 For (n=2) is 2.407934e-17 J.
 For (n=3) is 5.417852e-17 J. 
de-Broglie wavelength of electron -
 For (n=1) is 2.000000 A.
 For (n=2) is 1.000000 A. 
 For (n=3) is 0.666667 A
