Question

A mirror forms an erect image 40cm from the object and one third its height where must the mirror be situated ​

Answer 1

• image distance=-40cm=v
• Object distance=u=?
• Magnification=m=3

We know

`\boxed{\sf m=-(v)/(u)}`

`\\ \sf\longmapsto 3=-(-40)/(u)`

`\\ \sf\longmapsto 3=(40)/(u)`

`\\ \sf\longmapsto u=(40)/(3)`

`\\ \sf\longmapsto u=13.3cm`