Question

When the convex lens acts as a magnifying glass, the object is between the ___________ and the optical center of the lens.

Answer 1

Hint: Magnification of a device is the ability to produce an enlarged image of the object placed in front of it. Hence, mathematically it is the ratio of size of image to the size of the object. A convex lens can be used to produce both enlarged and diminished images of any object. Also it could be used to produce both real and virtual images of the object.

Complete step by step answer:
We have many cases for image formation in the case of convex lenses. One among these cases is that when the object is placed in between the optical centre (Centre of mirror) and the focus, it produces an enlarged image of the object. This could be illustrated by the help of the following diagram.

Here, we can see that the object is placed at a distance ‘u’ from the lens such that the image is formed at a distance ‘v’ from the lens. This is a virtual image which is obtained by extending the diverging rays in backward direction so that they meet at a point. We can clearly see that the size of the image is larger than the object itself.
Mathematically the magnification is given by $m = \dfrac{h_i}{h_o}$.
Hence we can say that a convex lens starts acting like a magnifying glass if the object is placed between focus and centre of lens.

Note:
Students are advised to note that the image formed in these types of cases is virtual and erect. Virtual because the image is formed by extending the rays in reverse direction. And erect because the image formed is oriented in the same way as the object (above principle axis).