Question

An object is placed at 30cm from convex lens and it's real image is formed at 20cm away from the lens calculate the focal length of lens ​

Answer 1

Answer:

Here,

Image distance=v=20cm,

Object distance=u=−30cm,

Lens equation is given by,

v1−u1=f1,

putting the values we get,

201−−301=f1,

∴f=12cm

∴ Focal length of convex lens=f=12cm