Internal Reflection and Dispersion

Practice Problems
Internal Reflection and Dispersion

Directions: On this worksheet you will examine several situations dealing with the behavior of different frequencies of light as they pass through transparent media.

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Question 1 In a physics olympics event, a semicircular plastic prism is used to direct light to a distant target on the wall. The prism has an index of refraction of n = 1.41 for red light and an index of refraction of n = 1.6 for green light. If a red beam strikes a streen L = 1.32 meters away at a position y = 0.22 meters above the central line, at what angle did the beam originally enter the prism?

13.3º9.5º13.4º6.7º

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Question 2 The beam of red light is now replaced by a beam of green light. If the green beam is aimed at the prism with the same entry angle as in Question #1, it will emerge

at a vertical position closer to the central line than the red beamat the same vertical position as the red beamat a vertical position farther from the central line than the red beam

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Question 3 A light ray enters a rectangular piece of glass along the path shown in the following diagram. If q₁ = 32º and q₂ = 53º at point A, then determine which of the following options will occur when the beam strikes point B.

the ray is internally reflected at an angle of 37ºthe ray is refracted back into the air at an angle of 58ºthe ray is internally reflected at an angle of 53ºthe ray is refracted back into the air at an angle of 45º

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Question 4 When surrounded by air, a beam of blue light normal to the hypotenuse of a 45-45-90 prism in internally reflected so as to bounce back out in the reverse direction from which it entered. What is the index of refraction of the material composing the prism?

1.871.501.711.41

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Question 5 If the prism in Question #4 were to be submerged in a liquid having an index of n = 1.31, what would happen when the beam arrives at the first diagonal interface?

it would escape out into the liquid at an angle of 49.8º to the normalit would escape out into the liquid at an angle of 67.9º to the normalit would continue to be internally reflected at an angle of 45ºit would travel in a completely vertical path, escaping out into the liquid at an angle of 45ºit would escape out into the liquid at an angle of 40.2º to the normal