Answer:
the index of refraction of the material is 1.53
Explanation:
c=40.8 degree
c = sin⁻¹ (n2/n1)
n2=1
then
For total internal reflection
sin40.8 = 1 / n1
0.6534 = 1 / n1
n1 = 1 / 0.6534
n1 = 1.53
Thus, the index of refraction of the material is 1.53