Question

Read the following conversation.
Teacher: "If you want to collect virtual images, which mirror do you select?"
Bharathi: "convex mirror"
Sowmya: "concave mirror"
Firoz: "plane mirror"
What do you think? Who is correct? Explain.

Answer 1

Hint: It is said that a concave mirror, a convex mirror and a plane mirror can be used to collect virtual images. We need to find which of them is most efficient. Since we need to collect virtual images, the mirror should be capable of always or mostly producing virtual images. Such a mirror that always or mostly produces virtual images can be used to collect virtual images.

Complete answer:
In the question we are given a conversation between a teacher and her students,
We can see that the students are arguing over which mirror gives a virtual image.
The first student says that convex mirrors always give virtual images.
This statement is correct because a convex mirror will always produce virtual images only. A convex mirror is also known as a diverging mirror because it diverges the light when they are incident on its reflecting surface. The image formed will always be virtual, erect and diminished irrespective of the distance between the object and the mirror. i.e. wherever we place the object we will always get a virtual image.
Therefore to collect virtual images we can use a convex mirror.
Now, the second student ‘Sowmya’ says that we can use a concave mirror to collect virtual images.
This statement of Sowmya is wrong. We can’t use concave mirrors to collect virtual images. In a concave mirror light converges at a point when it is incident and reflected back from the reflecting surface of the concave mirror and forms real images in most cases. But when we place an object in front of the focal point of a concave mirror, it will produce an upright image.
But as said in all other cases a concave mirror produces real images. Therefore we can’t use concave mirrors to collect virtual images.
It is said that Firoz says we can use plane mirrors to collect virtual images. This is also correct. Because plane mirrors always produce virtual upright images like convex mirrors. In a plane mirror the image will always have the same size of the object and the distance from object to mirror will be equal to distance from image to mirror.
Therefore we can use a plane mirror to collect virtual images.
Since plane mirrors and convex mirrors always give virtual images we can use them to collect virtual images. Hence Bharathi and Firoz are correct.

Note:
A surface that reflects a clear image is known as a mirror. Images are formed when a light falls on the mirror from the object and gets reflected back by the mirror to the screen.
The two types of images formed are real and virtual. A real image is an image that we can see on a screen whereas a virtual image is an image that can’t be seen on a screen.
Mirrors are mainly of two types; curved mirrors and plane mirrors. And when a curved mirror is a part of a sphere then it is called a spherical mirror. Spherical mirrors are again of two types; convex mirrors and concave mirrors.