Question

if an image distance and object distance for an object kept in front of an convex lens are 30cm and 20cm.calculate the focal length of an lense​

Answer 1

Answer:

focal length is 12 cm. . .

Explanation:

for a convex lens

focal length 1/f=1/u+1/v

Answer 2

focal length is 12cm

for a convex lens

focal length 1/f=1/u=1/v