![]() However, the emergent ray suffers some lateral displacement relative to the incident ray. ![]() Thus:įor a ray passing through the optical centre, the incident and emergent rays are parallel. It divides the thickness of the lens in the ratio of the radii of curvature of its two surfaces. In the given figure the optical centre of the lens. Optical centre: In the given figure if a ray of light is incident on a lens after refraction through the lens the emergent ray is parallel to the incident ray, then the point at which the refracted ray intersects, the principal axis is called the optical centre of the lens.Principal axis (C 1 C 2): It is the line passing through the two centres of curvature (C 1 and C 2) of the lens.R 1 and R 2 in the figure (a) and (b) represents radius of curvature. Radius of curvature (R): The radius of curvature of the surface of a lens is the radius of the sphere of which the surface forms a part.In figure (a) and (b) points C 1 and C 2 are the centres of curvature. Centre of curvature (C): The centre of curvature of the surface of a lens is the centre of the sphere of which it forms a part, because a lens has two surfaces, so it has two centres of curvature.Convex mirror :Convex mirror is the part of a hollow sphere whose outer surface acts as reflecting surface and the inner surface is silvered as shown in fig.ĭefinitions in connection with Spherical Lens:.Concave mirror : Concave mirror is the part of the hollow sphere whose outer surface is silvered and the inner surface acts as reflecting surface (fig.).Spherical mirrors are the reflecting part of spherical surface. Plane mirrors are used in periscopes usually used in submarines. Plane mirrors are used in a solar cooker to reflect the sun light. ![]() Plane mirror is used in a solar cooker to reflect the sun light. The image formed by a plane mirror is laterally inverted i.e., the left hand appears as right hand and vice-versa. Suppose, an object is placed at 5 cm in front of a plane mirror then its image will be at 5 cm behind he plane mirror. The image formed by a plane mirror is at the same distance behind the mirror as the object is in front of it. If object is 10 cm high, then the image of the object will also be 10 cm high. The size of the image formed by a plane mirror is same as that of the size of the object. The image formed by a plane mirror is erect. The image formed by a plane mirror is virtual. Characteristics of the image formed by a plane mirror In daily life when we see 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. A virtual image is seen only by looking into a the mirror or a lens. Virtual image formed by concave lens and convex mirrorīecause the image will not obtained on a the real screen then it is called a virtual image. Because the rays never really converge, one cannot project a virtual image. Then it will appear to converge in a point or behind the mirror or lens. In the same way, we can define virtual image as an image in which the outgoing rays from a point on the object always diverge from it. In this processes the image formed on the screen is real image. In the ray diagrams (such as the images on the right), real rays of light are always represented by full, solid lines that give the indication that it is real.Ī 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. In different types of mirror or lens the images appears are different some of the examples of real images includes the image seen on a cinema screen in this process the source or picture being the projector on screen, the image produced on a detector in the rear of a camera, and the image produced on an eyeball retina. If we will fix a screen in front of mirror or lens then a real image appear and the image will generally become visible on the screen. In study of light, Let an object O is placed then a real imageexist which the perceived location is actually a point of convergence of the rays of light that make up the image.
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