//Ex:8.18
clc;
clear;
close;
y1=550*10^-3;// peak of eyes response in um
y2=10.6;// standard wavelength in um
y3=2.39;// predominant IR line of He-Ne laser in um
E1=1.24/y1;// energy in electron volts
E2=1.24/y2;// energy in electron volts
E3=1.24/y3;// energy in electron volts
printf("The  energy =%f electron volts", E1);
printf("\n The energy =%f electron volts", E2);
printf("\n The energy =%f electron volts", E3);