The spherical side mirror on a car is convex and has a radius of curvature of 25 cm. Another car is following, 20 m behind the mirror. If the height of the car is 1.6 m, how tall is its image?

Answer 1

1/do+1/di=1/f is the equation, solve for di.

then, having di (remember the sign conventions for convex mirrors),

M=-di/do=hi/ho

Answer 2

f=-R/2; f=-25/2; f=-12.5

1/do+1/di=1/f
1/2000+1/di=1/-12.5
.0005+1/di=-.08
1/di=-0.0805
di=-12.42cm

1.6*di/do=1.6*2000/-12.42=-0.0099=1 cm