Answer: 2 cm
Explanation:
Given , for a converging lens
Focal length : [tex]f=20\ cm[/tex]
Height of object : [tex]h=1\ cm[/tex]
Object distabce from lens : [tex]u=-10\ cm[/tex]
Using lens formula: [tex]\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}[/tex], we get
[tex]\dfrac{1}{20}=\dfrac{1}{v}+\dfrac{1}{10}[/tex], where v = image distance from the lens.
On solving aboive equation , we get
[tex]\dfrac{1}{v}=\dfrac{1}{20}-\dfrac{1}{10}=\dfrac{1-2}{20}=\dfrac{-1}{20}\Rightarrow\ v=-20\ cm[/tex]
Formula of Magnification : [tex]m=\dfrac{v}{u}=\dfrac{h'}{h}[/tex] , where h' is the height of image.
Put value of u, v and h in it , we get
[tex]\dfrac{-20}{-10}=\dfrac{h'}{1}\\\\\Rightarrow\ h'=2\ cm[/tex]
Hence, the height of the image is 2 cm.