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

Here, `u = -30 cm, v = -60 cm`
As `1/f = 1/v + 1/u = 1/(-60) + 1/(-30) = - 1/20`
`f = -20 cm`,
The mirror is concave.
As the image is formed on the screen, it is real and inverted
From `h_(2)/h_(1) = (-v)/u = (+60)/(-30) = -2`
`h_(2) = -2h_(1) = -2 xx 2.4 cm = -4.8 cm`
This is the size of inverted image.