 

 ’’ a    a    ’ + a = 90 Therefore:   =   ’  

 ’’ a    b    ’ + b = 90 Therefore:   =   ’  ’’ b  

 a  b Sin     hyp   Sin     hyp Therefore: sin    =   sin   

Since v is proportional to sin      v 1 = constant sin     v 2 sin     sin     This constant is the relative refractive index, n

sin      v 1 = n 2 = n sin     v 2 n 1 Snell's Law