Eduprobe
Question:
Where should an object be placed in front of a convex lens to get a real image of the size of the object?
At infinity
At the principal focus of the lens
At twice the focal length
Between the optical centre of the lens and its principal focus
Solution:
The correct option is C. At twice the focal length.
When an object is kept at twice the focal length (2f) of a convex lens, the image is formed at twice the focal length (2f) on the opposite side. In this scenario, the magnification is -1. Magnification (m) is given by the formula: m = -v/u, where v is the image distance and u is the object distance. Since |v| = |u| = 2f, the magnification becomes m = -1. A magnification of -1 indicates that the image is real, inverted, and of the same size as the object.