**Total Internal Reflection Conceptual Question**

Part A = BCEF

Part B = E, B, F, C

**Solution Below:**

Part A

In order for total internal reflection to be possible, the source must have a greater index of refraction than the destination medium.

BCEF

Part B

You can use Snell’s law for this:

n_{1} * sin(θ_{1}) = n_{2} * sin(90)

Or:

n_{1} * sin(θ_{1}) = n_{2} * 1

So:

n_{1} * sin(θ_{1}) = n_{2}

For example, scenario B (water to air):

n_{1} * sin(θ_{1}) = n_{2}

1.33 * sin(θ_{1}) = 1.00

sin(θ_{1}) = 0.752

sin^-1(0.752) = 48.76°

You should notice that the reason scenarios like A are impossible is because you’d have to take the inverse sin of something greater than 1. This is why, in order for total internal reflection to be possible, the refractive index of the source must be greater than that of the destination.

For the different mediums, you get:

B = 48.76°

C = 24.41°

E = 62.46°

F = 33.34°

So the order from largest to smallest is:

E, B, F, C