If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

### Course: Class 10 Physics (India)>Unit 1

Lesson 2: Concave & convex mirrors and their applications

# Concave mirrors

In this video, we will see how concave mirrors focus a parallel beam of light to a single point.  Created by Mahesh Shenoy.

## Want to join the conversation?

• Why concave mirror is used as shaving mirror??
• Hey Rohit,
that's a good question. Using a concave mirror will give an enlarged and erected image of your face. This will make it easy to shave by seeing hair closely and clearly.
Keep up the curiosity!
don't forget to upvote though :)
• if there are non parallel rays hit a concave mirror will they also meet at focus?
• No, they do not meet at focus. Not all sets of parallel lines will meet at the focus either. I mean, they will converge at some point, but the focus is a special point. Only the lines parallel to the primary axis (the normal in the middle) will meet at the focus.
• If the focus is at 1 particular point wouldn't that mean that the doormat would have had to be in the parking lot very close to where the car got burnt?
• i think that AFTER meeting on the focus the rays of light continue on their path
• Is the true shape of a concave object a parabola?
(1 vote)
• Actually a concave mirror can be seen in any shape. It’s a part of the sphere of the reflecting surface and we don’t know how big the sphere is and how small is the part of the sphere which is used to make the mirror. There’s a difference between the parabolic mirror and the spherical mirror as the parabolic mirror is having a well defined focus will the sphere of the spherical mirror may not. So the concave mirror may appear to be in the shape of a parabola but it isn’t. It is a part of a whole big sphere. A parabolic mirror is the one which is having the focus at the centre just equidistant from both the sides of the mirror but it isn’t true in the case of a spherical mirror.
Hope this helps.
• What exactly would happen to a converging/diverging beam of light in this scenario? Would they meet at a focus too? Would that focus be the point of their convergence?
• The focus is always the point of the convergence of the light rays.As Mahesh explains that the light rays from the sun are always almost parallel they would always converge and meet at the focus point of the mirror.
(1 vote)
• how do we decide where the 'normal' rays are in a concave mirror
• In optics, a normal ray is a ray that is incident at 90 degrees to a surface. That is, the light ray is perpendicular or normal to the surface. The angle of incidence (angle an incident light ray makes with a normal to the surface) of the normal ray is 0 degrees... In case of a normal ray, no such refraction takes place.
(1 vote)
• Why does multiple(infinity) images form inside a plane mirror when two plane mirror are placed parallel are faced towards each other?
• Number of images formed in two parallel mirror are infinite because an image formed by one mirror can act as an object for the second mirror. And every image formed by the second mirror can act as an object for the first mirror. This image formation will continue for both the mirrors.
(1 vote)
• Is the light of sun and light produced in torch the same?
• The sun and a torch both emit energy in the form of particles called photons. The photons from the sun are a product of thermonuclear fusion. A torch uses a chemical reaction to burn. So the light produced by both of them are produced in the same way emitting light in all the areas with the sun or the torch being the source.
(1 vote)
• Why this tower is called Walkie Talkie tower??