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N An object is placed a distance of 10.0 cm to the left of a thin converging len

ID: 1521336 • Letter: N

Question

N An object is placed a distance of 10.0 cm to the left of a thin converging lens of focal length f = 8.00 cm, and a concave spherical mirror with radius of curvature + 18.0 cm is placed a distance of 45.0 cm to the right of the lens (Fig. P38.129). 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? b. What is the magnification of the final image as seen by an observer positioned to the left of the object? c. Is the final image formed by the lens mirror combination upright or inverted?

Explanation / Answer

by lens equation

1 / f = 1 / u + 1 / v

1 / 8 = 1 / 10 + 1 / v

v = 40 cm

position of the image by lens as seen by observer = 40 + 10

position of the image by lens as seen by observer = 50 cm

let the height of the object be x so

height of the image / heigh of the object = -distance of the image / distance of the object

height of the image / x = -40 / 10

height of the image = -4x

radius of curvature of mirror = 18 cm

focal length = radius of curvature / 2

focal length = 18 / 2

focal length = 9 cm

position of the object = 45 - 40

position of the object = 5 cm

by mirror equation

1 / f = 1 / u + 1 / v

1 / 9 = 1 / 5 + 1 / v

v = -11.25 cm

height of the image / heigh of the object = -distance of the image / distance of the object

height of the image / 4x = -(-11.25) / 5

height of the image = 9x

magnification = 9

final image formed by lens mirror combination will be inverted