) Consider a beam of light traveling from a medium with a low index of refraction n1 to a new medium with a higher index of refraction n2. Use Snell’s Law to explain why total internal reflection will never occur in this situation, regardless of the choice of the incident angle.

Snell's law says that

n1*sin(a1) = n2*sin(a2)

n1 < n2

son n2/n1 > 1

then:

sin(a1) = (n2/n1)sin(a2)

the maximum possible value of sin(x) is 1 when x =90°

total internal reflection means that a2= 90°

but as the coefficient that is multiplying sin(a2) is bigger than 1, we can not have a2 = 90°, because the right side will be greater than 1 and the left side can not be bigger than 1, so we can not have a2 = 90°, so we can not have total internal reflection