Understanding Total Internal Reflection

What are the two conditions necessary for total internal reflection to occur?

• Light must travel from a higher to a lower index of refraction and the angle of incidence must be less than the critical angle.

• Light must travel from a lower to a higher index of refraction and the angle of incidence must be greater than the critical angle.

• Light must travel from a higher to a lower index of refraction and the angle of incidence must be greater than the critical angle.

• Light must travel from a lower to a higher index of refraction and the angle of incidence must be less than the critical angle.

According to Snell's Law, what happens to light when it passes into a material with a lower index of refraction?

• It bends towards the normal line.

• It continues in a straight line.

• It bends away from the normal line.

• It reflects back into the original material.

What is the critical angle?

• The angle of refraction that results in an angle of incidence of 90 degrees.

• The angle of refraction that results in total reflection.

• The angle of incidence that results in total reflection.

• The angle of incidence that results in an angle of refraction of 90 degrees.

What occurs when the angle of incidence exceeds the critical angle?

• All light is absorbed by the boundary.

• All light is refracted into the second material.

• All light is reflected back into the original material.

• Light is partially refracted and partially reflected.

Which formula is used to calculate the critical angle?

• cos(critical angle) = N2 / N1

• sin(critical angle) = N2 / N1

• sin(critical angle) = N1 / N2

• cos(critical angle) = N1 / N2

In the critical angle formula, what does N1 represent?

• The index of refraction of the material the light is entering.

• The index of refraction of the material the light is leaving.

• The angle of incidence.

• The angle of refraction.

What is the sine of 90 degrees used for in the critical angle calculation?

• To determine the angle of incidence.

• To simplify the equation as it equals one.

• To determine the angle of refraction.

• To simplify the equation as it equals zero.

If the index of refraction for air is 1.0 and for water is 1.33, what is the critical angle?

• 75 degrees

• 90 degrees

• 48.6 degrees

• 60 degrees

What must be true for total internal reflection to occur in a water-air boundary?

• The angle of incidence must be less than 48.6 degrees.

• The angle of incidence must be exactly 48.6 degrees.

• The angle of incidence must be greater than 48.6 degrees.

• The angle of incidence must be 90 degrees.

What happens to light when it is shone at an angle greater than the critical angle in a water-air boundary?

• It is completely refracted into the air.

• It is completely absorbed by the boundary.

• It is completely reflected back into the water.

• It is partially refracted and partially reflected.