9th grade physics
posted by Cathy on .
If a transparent material has a refractive of 2.0;
a) calculate the critical angle
b) if the refractive index were less than 2,0, would the critical angle be greater or less than before?
Im super confused at this :(

If a ray of light INSIDE a medium of index N is incident at an angle of A or more upon a surface with index 1.00 outside, the light will be totally reflected. A is called the critical angle. It is given by the equation
sinA = 1/N
(a) In this case, N = 2, so
A = sin^1 (1/2) = 30 degrees
(b) If N<2,
sin A > 1/2 and A > 30 degrees.
The answer is "greater".