Question

the focal length of a convex lens is 3 cm. draw the ray diagram of an object placed on the principal axis at a distace of 6cm​

Answer 1

Explanation:

Image distance=v=20cm,

Object distance=u=−30cm,

Lens equation is given by,

v

1

−

u

1

=

f

1

,

putting the values we get,

20

1

−

−30

1

=

f

1

,

∴f=12cm

∴ Focal length of convex lens=f=12cm