Question

at what distance a watch maker musthold his lens from the watch ? options 1 at the focal length 2 At lass then focal length 3 more than the focal length 4 zero distance​

Answer 1

Answer:

2. Less than the focal length

Explanation:

This is because he needs a virtual and erect and enlarged image of the watch, which can only be achieved using the convex lens and placing the object, the watch in this case, at a distance lesser than the focal length, ie, between F and O (u<f) so that a magnified image, that is virtual and erect is formed.