A light ray in air (n = 1.00) strikes a flat piece of glass (n = 1.50) at an angle of incidence of 40°. What is the angle of refraction? (Use sin 40° = 0.643 and arcsin(0.429) = 25.4°)
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Correct answer
A. 25.4°
Principle or equation
Snell's law: n1 sin θ1 = n2 sin θ2.
Why this answer is correct
Using Snell's law: 1.00 × sin 40° = 1.50 × sin θ2. So sin θ2 = 0.643 / 1.50 = 0.429. Therefore θ2 = arcsin(0.429) = 25.4°.
Example
For air to glass with n = 1.50 and angle of incidence 40°, the angle of refraction is 25.4°.
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