The side mirrors on cars are convex mirrors. If the side mirror on the driver side of your car has a focal length with a magnitude of 5.40 m and a truck is at a distance of 3.00 m from the mirror, determine the following. Required:
a. Image distance of the truck (Include the appropriate positive or negative sign.)
b. Magnification for this object distance (Include the appropriate positive or negative sign.)

Explanation:

Image distance and focal length of a convex mirror is negative.

a) Using the mirror formula to determine the image distance;

f = focal length of the mirror = -5.40m

u = object distance from the mirror = 3.00m

v = image distance from the mirror

b) Magnification = image distance/object distance

Magnification = 1.93/3

Magnification = +0.643

Note that we do not use the negative value of the image distance to calculate the magnification of the object

think its the third option