Real images and virtual images

Real images and virtual images 

(1) Real images- 

 The image which can be obtained on a screen is called a real image . 

In a cinema hall , we see the images of actors and actresses on the screen. So, the images on a cinema screen is an example of real images. A real image is formed when light rays coming from an object actually meet at a point after reflection from a mirror ( or refraction through a lens ). A real image can be formed on a screen because light rays actually pass through a real image. Real images can be formed by a concave mirror. A convex lens can also form real images.

(2) Virtual images-

 The image which cannot be obtained on a screen is called a virtual image . A virtual image can be seen only by looking into a mirror ( or a lens) . The image of our face formed by a plane mirror cannot be obtained on a screen, it can be seen only by looking into the mirror. So the image of our face in a plane mirror is an example of virtual image. Virtual images are also called unreal images. A virtual image is just an illusion.

      A virtual image is formed when light rays coming from an object only appear to meet at a point when produced backwards ( but do not actually meet) after reflection from a mirror (or refraction through a lens). 

       A virtual image cannot be formed on a screen because light rays do not actually pass through a virtual image. A plane mirror always forms virtual images. Similarly, a convex mirror also forms only virtual images. A concave mirror can form a virtual image only when the object is kept within its focus.