Question

How would a pencil look if you see it through a convex lens? (Assume that the pencil is close to the lens) Is the image real or virtual?

Answer 1

Hint: A convex lens is one which converges the light coming from infinity parallel to the principal axes to a point on the other side of lens, that point is known as focus whereas Convex lens is also known as converging lens, we will draw the ray diagram in order to find the nature of image of the pencil formed by the convex lens.

Complete step by step answer:
According to the question, let us suppose a pencil is placed near the convex lens, let us suppose $F$ is the focus point of the convex lens and $O$ is the centre of the lens.As we know that light rays coming from the object parallel to the principal axes will pass through the focus of the convex lens after refraction while light rays which come from the object passing through the centre $O$ of the convex lens will not deviate so they will be a straight line.

The formation of image of the pencil by convex lens is shown as in the diagram,

From the ray diagram, we can see that the image of the pencil will be formed erect, magnified which is virtual.

Hence, the image will be virtual and will form on the same side of the object.

Note: It should be remembered that a virtual image is always magnified which means the image is larger in size compared to objects height and it’s erect. Also, in the case of a concave lens which is a diverging lens, parallel rays of light coming from infinity get diverged after getting refracted through the concave lens.