Question

A convex mirror with a focal length of –20.0 cm forms an image 12 cm behind the surface. Where is the object as measured from the surface?

Answer 1

Given

The focal length is f= -20 cm

The image distance is v= -12cm

To find

The object distance

Step-by-step explanation

The mirror formula is

`\begin{gathered} (1)/(f)=(1)/(u)+(1)/(v) \\ \Rightarrow(1)/(^-20)=(1)/(u)+(1)/(^-12) \\ \Rightarrow u=30cm=3.0*10\text{ cm} \end{gathered}`

Conclusion

The object distance is 30x10 cm.