The mirror equation states the quantitative correlation among the object distance (do), the image distance (di), and the focal length (f).
f - Focal length,
di - Image distance,
d0 - Object distance.
A 4.0-cm tall light bulb is placed a distance of 35.5 cm from a concave mirror having a focal length of -12.2 cm. Determine the image distance and the image size.
h 0 = 4.0 cm
d 0 = 35.5 cm
f = -12.2 cm
Image distance (di)
Substitute the values in the formula.
1/f = 1/d0 + 1/di
1/(-12.2 cm) = 1/(35.5 cm) + 1/di
-0.0820 cm-1 = 0.0282 cm-1 + 1/di
-0.110 cm-1 = 1/di
image distance (di) = -9.08 cm
Learn how to calculate Mirror equation in this tutorial, given with the definition, formula and example.