Geometric Optics unit test
A test on this unit alone, marked as a percentage and a letter grade — for the test your class is actually sitting, rather than for May. Answer everything, then submit once: seeing the answer to question 3 before attempting question 4 makes the final percentage meaningless.
Fiber optics and prisms
Index of refraction
Concave versus convex mirror
Why the image of a half-covered lens is dimmer, not halved
Real image on a screen
Three principal rays for a converging lens
Two forms of magnification
Total internal reflection
Wavelength in a medium
Real vs virtual images
Snell's law
Critical angle
Short answer 1. Define or explain: Focal length and radius of curvature
3 ptsShort answer 2. Define or explain: Convex mirror
3 ptsShort answer 3. Define or explain: Predicting image type without calculating
3 ptsShort answer 4. Define or explain: Plane mirror image
3 ptsFree response
8 ptsAn object is placed a distance 3f in front of a thin converging lens of focal length f. The same object is then placed the same distance 3f in front of a second thin converging lens whose focal length is 2f.
A. Indicate whether the image formed by the second lens is larger than, smaller than, or the same size as the image formed by the first lens. Justify your answer using qualitative reasoning beyond referencing equations.
B. Starting from the thin-lens equation, derive expressions for the image distance and the magnification produced by a converging lens of focal length f when the object is at distance 3f.
C. Justify how your derived expressions in part B are or are not consistent with your comparison in part A.