Reflection AP Physics 2 FRQ – Exam Style Questions etc.
Reflection AP Physics 2 FRQ
Unit 13: Geometric and Physical Optics
Weightage : 15–18%
Exam Style Practice Questions , Reflection AP Physics 2 FRQ
Question
In the graphs that follow, a curve is drawn in the first graph of each pair. For the other graph in each pair, sketch the curve showing the relationship between the quantities labeled on the axes. Your graph should be consistent with the first graph in the pair.
Answer/Explanation
Ans:
e) Based on 1/f = 1/do + 1/di
Rearrange for y as function of x (make f – since concave) 1/di = (–1/f) + (–1/do) .. the focal point term is negative and constant so …As do increases the 1/do term decreases adding less and less – values to the right side of the equation. When do gets very large the right side becomes constant.
Question
A right angle prism with an index of refraction of n=1.84 is shown at right. What is the maximum angle of incidence on the prism face such that total internal reflection does not occur on the back face of the prism?
Answer/Explanation
Ans: 24.4°
First find the critical angle for the back face: \(sinθ_{C} =\frac{ 1}{n_{prism}}→ θ_C = sin^{−1}\frac{ 1}{n_{prism}} = sin^{−1} \frac{1}{ 1.84}= 33°\)
Next, note that a ray incident on this back face at this angle would make an angle of 57° with the back face \((θ_3)\). 
This would lead to a refracted angle of 17° at the prism face (\(θ_4\) =73°). Applying Snell’s Law, the incident angle is determined as 32.5°.