Answer :
Image distance = -2.4 cm
Height of image = 7.2 cm
Concave lens
Explanation :
Given that,
Height of the object, h = 9 cm
Object distance, u = 3 cm
Focal length, f = -12 cm
Using mirror's formula
[tex]\dfrac{1}{f}=\dfrac{1}{u}+\dfrac{1}{v}[/tex]
[tex]\dfrac{1}{v}=\dfrac{1}{f}-\dfrac{1}{u}[/tex]
[tex]\dfrac{1}{v}=\dfrac{1}{(-12)}-\dfrac{1}{(3)}[/tex]
v = -2.4 cm
Image distance is 2.4 cm from the lens.
Magnification, [tex]m =\dfrac{-v}{u}=\dfrac{h'}{h}[/tex]
[tex]h'=\dfrac{-vh}{u}[/tex]
h' = 7.2 cm
The height of the image is 7.2 cm. This shows that the image is upright.
The lens used is concave lens.
