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The writing on the passenger-side mirror of your car says \"Warning! Objects in

ID: 1500155 • Letter: T

Question

The writing on the passenger-side mirror of your car says "Warning! Objects in mirror are closer than they appear" (Figure 1) . There is no such warning on the driver's mirror. Consider a typical convex passenger-side mirror with a focal length of -80 cm. A 1.7-m-tall cyclist on a bicycle is 28 m from the mirror. You are 1.0 m from the mirror, and suppose, for simplicity, that the mirror, you, and the cyclist all lie along a line.

How far are you from the image of the cyclist?

How far would you have been from the image if the mirror were flat?

What is the image height?

What would the image height have been if the mirror were flat?

Explanation / Answer

for convex mirror,

f = - 80 cm

object distance, do = 28 m = 2800 cm

Applying mirror equation,

1/f= 1/do + 1/di

1/(-80) = 1/2800 + 1/di

di = - 77.78 cm = - 0.778 m


distance of image from passenger = 100 + 77.78 - 177.78 cm Or 1.78 m   .......Ans


if mirror was flat then di = do

hence di = 28 m

distance of image = 28 + 1 = 29 m Or 2900 cm ..........Ans


Magnification = hi/ho = - (di / do)

hi / 1.7 = - (-77.78) / 2800

hi = 0.0472 m Or 4.72 cm .......Ans

for flat mirror,

hi = ho

hi = 1.7 m ,,,,,,,,,,,,,,aNS