Question

Find the image distance of an object placed 5.00 cm in front of a convex mirror whose focal length is 8.00 cm.

Answer 1

The mirror equation is given by:

`(1)/(d_o)+(1)/(d_i)=(1)/(f)`

Where d0 is the distance to the object, di is the distance of the image and f is the focal length. In this case we have that:

• The distance of the object is 5 cm

,

• The focal length is 8 cm.

Plugging these and solving for di we have that:

`\begin{gathered} (1)/(5)+(1)/(d_i)=(1)/(8) \\ (1)/(d_i)=(1)/(8)-(1)/(5) \\ (1)/(d_i)=(5-8)/(40) \\ (1)/(d_i)=-(3)/(40) \\ d_i=-(40)/(3) \\ d_i=-13.33 \end{gathered}`

Therefore, the image distance is -13.33 cm. Note: the minus sign indicates that the image is behind the mirror, that is, the image is virtual.