Object and Image
Object and Image :- In Optics for a mirror object and image, both can be real or virtual.
Object :- Source of light is known as object.
- Real Object :- A point from which light rays are actually emitted and fall on a mirror(or any reflecting/refracting surface) is said to be a real object. In other words if the incident rays(as seen from the mirror) are diverging, then the point of divergence is the position of real object.
- Virtual Object :- A point at which incident light rays(as seen from the mirror) appear to converge is said to be a virtual object. In other words if the incident rays are converging, then the point of convergence is the position of virtual object.
Conceptual Note :- Virtual object cannot be seen by human eye, because for an object or an image to be seen by the eyes, the light rays received by the eyes must be diverging.
Image :- An optical image is a point at which reflected(or refracted) rays actually meet(real Image) or appear to meet or diverge from(virtual image).
- Real Image :- If the light rays after reflection(or refraction) actually meet(or converge) at a point then the image is said to be real.
- Virtual Image :- If the light rays after reflection(or refraction) do not actually meet at a point but appear to diverge from a point(or appear to meet at a point), then the image is said to be virtual.
Conceptual Note :-
1. A real image can be obtained on a screen but a virtual image cannot be taken on a screen.
2. The convex lens in human eye enables us to see virtual images because this convex lens converges the light rays diverging from a virtual image on the retina.
3. Human eye cannot distinguish between the real image and the virtual image because in both the cases the rays are diverging.
Important Note :- In short the point which is related to the incident rays is an object and the point which is related to the reflected(or refracted) rays is an image.