Light enters a glass block (n = 1.5) from air (n = 1.0) at an angle of incidence of 30 degrees. What is the angle of refraction? (sin 30 = 0.5, sin 19.5 = 0.333)
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Correct answer
A. 19.5 degrees
Principle or equation
Snell's law: n1 sin θ1 = n2 sin θ2.
Why this answer is correct
1.0 * sin 30 = 1.5 * sin θ2 => sin θ2 = 0.5/1.5 = 0.333, so θ2 = 19.5 degrees.
Example
For n2=1.33 (water) and θ1=45, sin θ2 = sin45/1.33 ≈ 0.532, θ2≈32.1 degrees.
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