Question

3. The size of image formed by a convex lens when the object is placed at the focus of convex lens is (a) small (b) point in size (c) highly magnified (d) same as that of object ​

Answer 1

Answer:

When an object is placed at a distance further than the focal distance of a convex lens, light rays originating from any point on the object will be refracted by the lens such that they will form a real but inverted image of the object on the opposite side of the lens (Figure 4, A).

Answer 2

The size of image formed by a convex lens when the object is placed at the focus of convex lens is HIGHLY MAGNIFIED.

But why?

• Usually, when axial light rays from objects place at infinity undergo refraction through a convex lens, they produce a small real image at the focus.

• Similarly, when objects are placed at the focus light rays originating from the object undergo refraction to produce a large image.

• This highly magnified real image is produced at a far away point (i.e. at infinity).

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