Answer: 2 cm
Explanation:
Given , for a converging lens
Focal length : ![f=20\ cm](https://tex.z-dn.net/?f=f%3D20%5C%20cm)
Height of object : ![h=1\ cm](https://tex.z-dn.net/?f=h%3D1%5C%20cm)
Object distabce from lens : ![u=-10\ cm](https://tex.z-dn.net/?f=u%3D-10%5C%20cm)
Using lens formula:
, we get
, where v = image distance from the lens.
On solving aboive equation , we get
![\dfrac{1}{v}=\dfrac{1}{20}-\dfrac{1}{10}=\dfrac{1-2}{20}=\dfrac{-1}{20}\Rightarrow\ v=-20\ cm](https://tex.z-dn.net/?f=%5Cdfrac%7B1%7D%7Bv%7D%3D%5Cdfrac%7B1%7D%7B20%7D-%5Cdfrac%7B1%7D%7B10%7D%3D%5Cdfrac%7B1-2%7D%7B20%7D%3D%5Cdfrac%7B-1%7D%7B20%7D%5CRightarrow%5C%20v%3D-20%5C%20cm)
Formula of Magnification :
, where h' is the height of image.
Put value of u, v and h in it , we get
![\dfrac{-20}{-10}=\dfrac{h'}{1}\\\\\Rightarrow\ h'=2\ cm](https://tex.z-dn.net/?f=%5Cdfrac%7B-20%7D%7B-10%7D%3D%5Cdfrac%7Bh%27%7D%7B1%7D%5C%5C%5C%5C%5CRightarrow%5C%20h%27%3D2%5C%20cm)
Hence, the height of the image is 2 cm.