1(vii)
A convex lens with a focal length of 12 cm has an object at a distance of 20 cm in front of the lens. A blurred image is obtained on the screen placed at a distance of 23 cm in front of the lens. In order to obtain a clear image, the screen has to be moved:
- (a)towards the lens.
- (b)away from the lens.
- (c)to a position very far away from the lens.
- (d)either towards or away from the lens.
Show SolutionHide Solution↓
away from the lens.
Reason —
Given,
Focal length (f) = +12 cm
Object distance (u) = -20 cm
Blurred image distance (v') = +23 cm
From the given information we can conclude that the object is placed between F1 and 2F1 of the convex lens. So, the image will be formed beyond 2F2 i.e., the image distance will be greater than 24 cm.
Hence, in order to obtain the clear image, the screen should be moved away from the lens.