AP Physics 2 Practice Question 1
What happens to the image formed by a concave mirror as the object is moved from far away to near the focal point?
Correct Answer: B
B One way to answer this question is to invent some numbers that satisfy the conditions of the question and observe what happens. Let’s choose f = 1 m, and take so1 = 3 m and so2 = 2 m (notice that f < so2 < so1, which means that the object is moving closer to the focal point). Using the mirror equation, we find that
Since si2 > si1, the image is moving away from the mirror (eliminating (C) and (D)). Now for the magnifications:
Since |M2|>|M1|, the image gets taller. (You can also use ray diagrams.)