An object 4 cm in height, is placed at 15cm in front of a concave mirror of focal length 10 cm. At what distance from the mirror should a screen be placed to obtain a sharp image of the object? Calculate the height of the image?

Explanation

`h_1 = + 4 cm` f = - 10 cm u = -15 cm v = ? `h_2` = ?
`1/f = 1/v + 1/u`
`implies 1/v = 1/f - 1/u`
`1/v = (1)/(- 10 cm) - (1)/(- 15 cm)`
`:. v = -30 cm`
`(h_2)/(h_1)= - v/u`
`:. h_2= - v/u xx h_1 = - (-30cm)/(-15 cm) xx 4 cm` = -8 cm