An object of length 2.5 cm is placed at a distance of 1.5 f from a concave mirror where f is the magnitude of the focal length of the mirror. The length of the object is perpendicular to the principal axis. Find the length of the image. Is the image erect to inverted?

Explanation

The given situation is shown in ure.
The focal length `F=-f and u=-1.5f, we have `
`1/u+1/v=1/F or, 1/(-1.5f)+1/v=1/(-f)`
`or 1/v=1/(1.5f)-1/f=(-1)/(3f)`
`or v=3f`
`Now m=-v/u=(3f)/(-1.5f)=-2`
or `h_2/h_1=-2 or h_2=2h_1=5.0cm.`
The image is 5.0 cm long. The minus sign shows that it in inverted.