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Questions 5 and 6 refer to a beam of light that passes through a sheet of plastic and out into the air. The angle the beam of light makes with the normal as it passes through the plastic is (theta1), and the angle the beam of light makes with the normal as it passes into the air is (theta 2). The index of refraction for air is 1 and the index of refraction for plastic is 2.

5. What is the value of sin(theta 2), in terms of (theta 1) ?
(A) (1/2)sin (theta 1)
(B) 2 sin (theta 1)
(C) sin 2 (theta 1)
(D) sin (1/2)(theta 1)
(E) 4 sin (theta 1)


My question is why it says the answer is A. Snell's law is n1Sin(theta1) = n2Sin(theta2) so if (theta1) refers to the plastic, and n1 is for plastic too, which is 2, then that means (theta 2) is for the air with the n2 value of 1.

n1Sin(theta1) = n2Sin(theta2)
2Sin(theta1) = 1Sin(theta2)

So doesn't this mean the answer is B?

By Collegebound123 (Collegebound123) on Friday, October 08, 2004 - 01:29 pm: Edit

Yup -- I had the same problem. You'll come across many more errors in Sparknotes.