Question

How can converging lenses produce magnified images?
(A) When object is beyond of 2F
(B) When object is at C
(C) When object is at F
(D) When object is behind the mirror

Answer 1

Hint : We need to draw the images of the ray diagrams for solving this question. We need to keep in mind the laws of refraction and using those we can find the position of the object in front of a converging lens when the image is magnified.

Complete step by step answer
A converging lens is also called a convex lens. The rays of light that enter parallel to its principal axis converge at a single point on the opposite side. Real images are formed by the converging rays of light.
We need to be familiar with a few terms before we proceed. The horizontal axis containing the centre of curvature is known as the principal axis. The centre of curvature is the point where the incident ray passes without any deviation in its path.
Unlike mirrors, which only have one face, lenses have two faces and allow light to pass through either face, no matter from which direction the light comes from. Focal point, F of the lens is a point at which parallel light rays incident on the lens converge. There are two focal points on either side of the lens. The distance from the centre of the lens(C) to the focal point (F) is the focal length (represented by $f$ ). Twice the focal length from the centre of curvature is the point, 2F. This is an imaginary point.
Now let us consider the first situation given in the question.
The situation is such that the object is placed beyond 2F. We shall draw the figure for this.

$\therefore$ A magnified image is produced when the object is between focus and centre of curvature of a convex lens. By altering the values of focal length for a lens, it can be said that a magnified image was produced by placing the object at F.
$\therefore$ The correct answer is option C.

Note
Converging lens magnifies images to produce erect, magnified images. Hence, these converging lenses are used as magnifying lenses for practical uses.