A convex mirror has a radius of curvature whose magnitude is 47 cm. The mirror i
ID: 1787850 • Letter: A
Question
A convex mirror has a radius of curvature whose magnitude is 47 cm. The mirror is positioned on a horizontal optical bench with its front surface at 0 cm. A 12.5 cm long fluorescent lamp oriented vertically is placed at +110 cm. What is the focal length of the mirror?
At what distance from the mirror can we find a sharp image of the lamp?
how tall is the image of the lamp?
if the convex mirror were replaced by a plane mirror and the lamp moved to 188 cm from the plan mirror, how tall would the image be?
Explanation / Answer
a) focal length = -R / 2 = -47 / 2
focal length of the mirror = -23.5 cm
b) 1/f = 1/p + 1/q
1/q = 1/-23.5 - 1/110
distance from the mirror q = -19.36 cm
c) m = h'/h = -q/p
h' = 19.36/110 *12.5
= 2.2 cm
d) 12.5 cm