Question

Draw a diagram to represent the nature, position and relative size of the image formed by a
i) Convex lens for the object placed at 2F
ii) Concave lens for the object placed between F and 2F

Answer 1

Hint: In this question, we start with the convex lens which is also a converging lens and when we place the object at 2F the image we get is real, inverted, of the same size, and at 2F on the opposite side of the lens. Similarly, we take a concave lens which is also a diverging lens and when we place the object between F and 2F the image we get is Virtual, non-inverted, of smaller size and at distance less than F on the same side of the lens.

Complete Step-by-Step solution:
Let us take a principle axis and place a lens with the focal point as F
I) A convex lens is also known as a converging lens so it can be used to get a real image and we get an inverted image because we have placed the object at a distance greater than the focal length of the convex lens as shown in figure 1. Here the object is placed at a 2F distance from the center of the lens, so the image is formed at 2F but it is on the other side of the lens and it is of equal size as that of the object.

Figure 1

ii) A concave lens is also known as a diverging lens so it can be used to get a virtual image and we get a non-inverted image because we have placed the object at a distance greater than the focal length of the concave lens as shown in figure 2.Here object is placed between F and 2F so, the image is formed at a distance less than F and it is smaller than the original object.

Figure 2

Note: For these types of questions, we need to know the nature of the image formed by a convex lens, concave lens, convex mirror, concave mirror, and plane mirror for different positions of the object. The image may be real or virtual, inverted or non-inverted, and Size it’s may vary depending upon its position and the type of lens or mirror used.