An object of height 3 cm is placed at 10 cm from a concave lens of focal length 15 cm. find the size of the image.

Explanation

u=- 10cm [left side of lens]
f=- 15 cm [left side of lens]
h=3cm
`m=(v)/(u)=(-6)/(-10)=0.6`
`m=(h)/(h)rArrh.mxxh`
`h.=0.6xx3`
`h=1.8cm`
`(1)/(f)=(1)/(v)-(1)/(u)`
`(1)/(v)=(1)/(f)+(1)/(u)`
`=(1)/(-15)+(1)/(-10)`
`(1)/(v)=-(1)/(15)-(1)/(10)=(-10-15)/(15)=(-25)/(150)`
`(1)/(v)=-(1)/(6)`
`v=-6cm`
Nature of image : When an object is placed at 10cm from left side of the lens , a virtual image is formed between optical center and focus of a concave lens The size of image is smaller than of the object.