PLC Activity #14
Refraction and Lenses
Due: see website for due date
How to get credit for this activity
First, sign-in at the computer and sign-out when the activity is complete. Show your work
and results to a PLC tutor so they can check your work and initial the signoff sheet. Be
prepared to answer questions about the activity or your results.
Question 1 (Physlet Problem 34.2)
A light beam source, in air, is incident on a substance of unknown index of
refraction. You can click-drag both the position and the ray angle of the beam. You can
move the pink protractor around and use it to measure angles. What is the index of
refraction of the unknown substance?
Question 2 (Physlet Problem 35.1)
Four regions are hidden by curtains. You can drag the source of light to any location.
a. What is behind each curtain?
b. Rank the objects in terms of their focal lengths from smallest to largest (most
negative to most positive).
Question 3
In the figure below, stick figure 0 stands in front of a thin lens that is mounted within the
boxed region; the central axis through the lens is shown. The four stick figures I1 to I4
suggest general locations and orientations for the images that might be produced by the
lens. (The figures are only sketched in; neither their heights nor their distances from the
lens are drawn to scale.) (a) Which of the stick figures could not possibly represent
images? Of the possible images, (b) which would be due to a converging lens, (c) which
would be due to diverging lens, (d) which would be virtual, and (e) which would involve
negative magnification?
Question 4
The figure below shows three situations in which the stick figure stands in front of a thin
lens; the focal points F are indicated. For each situation determine whether (a) the focal
length, (b) the image distance, and (c) the magnification are positive or negative.