An object is placed a distance of 15.0 cm to the left of a thin converging lens
ID: 1521005 • Letter: A
Question
An object is placed a distance of 15.0 cm to the left of a thin converging lens of focal length f= 7.40 cm, and a concave spherical mirror with radius of curvature +15.5 cm is placed a distance of 39.6 cm to the right of the lens (see figure below) (a) What is the location of the final image formed by the lens-mirror combination as seen by an observer positioned to the left of the object? x11.2 The correct answer is not zero. cm to the left of the mirror (b) What is the magnification of the final image as seen by an observer positioned to the left of the object? (Include the sign of the value in your answer.) | 0.439 The correct answer is not zero. (c) Is the final image formed by the lens-mirror combination upright or inverted? o upright O invertedExplanation / Answer
a)
for the converging lens :
f = 7.40 cm
do = object distance = 15 cm
di = image distance
using the lens equation
1/f = 1/di + 1/do
1/7.40 = 1/di + 1/15
di = 14.6 cm
for the mirror :
f = R/2 = 15.5/2 = 7.75 cm
do = object distance = 39.6 - 14.6 = 25 cm
using the mirror equation
1/f = 1/di + 1/do
1/7.75 = 1/di + 1/25
di = 11.2 cm to left of mirror
b)
magnification for lens :
m1 = - di/do = - 14.6 / 15 = - 0.97
final magnification :
m = - 0.97 (- 11.2/25) = 0.43
c)
the image is upright