The image of a candle flame placed at a distance of 30 cm from a mirror is formed on a screen placed in front of the mirror at a distance of 60 cm from its pole. What is the nature of the mirror ? Find its focal length. If the height of the flame is 2.4 cm, find the height of its image. State whether the image formed is erect or inverted.

Explanation

`h_1` = 2.4 cm, u = - 30 cm, v = - 60 cm, f = ?
`1/f = 1/v + 1/u`
`=(1)/(-60 cm)+(1)/(-30 cm)`
`:. f = -20 cm`
`m=(h_2)/(h_1)=v/u`
`:. h_2= -h_1 xx v/u = -2.4 xx (-60 cm)/(-30 cm)` = -4.8 cm
(-ve sign of `h_2` (image size) in indicates that the image is inverted)