Question

An object is placed at a distance of 60 cm from a concave lens of focal length 30cm.find the position and nature of the image?

Answer 1

Answer:

using the lens formula: 1/f = 1/u + 1/v

focal length f = -30 (negative because it is concave lens)

object distance u = 60

image distance v= unknown

1/-30 = 1/60 + 1/v

v = -20

So, the image is 20cm from lens (on the same side along with the object), and it is virtual (because of negative sign) and erect (concave lens must produce erect images).