Derive the Lens Makers equation
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Derive lens makers' equation. Why is it called so? Under which conditions focal length f and radii of curvature R are numerically equal for a lens?

The lens maker's equation is given by

A convex lens (with material of refractive index of 3/2) has two surfaces of equal radii of curvature R. The magnitude of its focal length is

A plano-convex lens fits exactly into plano-concave lens as shown in the figure. Their plane surfaces are parallel to each other. If the lenses are made of different materials of refractive indices 1.6 and 1.5 respectively, if R is the radius of curvature of curved surface of lenses, then the focal length of the combination

A plano-convex lens fits exactly into a plano-concave lens. Their plane surfaces are parallel to each other. If the lenses are made of different material of refractive indices mu_(1) and mu_(2) and R is the radius of curvature of the curved surface of the lenses, then focal length of the combination is

The object which are at large distance as compared to the focal length of lens (greater than 10xxf ) are referred as _____

What is achromatism? Derive a condition to achieve achromatism for a lens combination. State the conditions for it to be converging

The equiconvex lens has focal length f. If is cut perpendicular to the principal axis passing through optical centre, then focal length of each half is

Read the following paragraph and answer the following questions given below it : Construction of a compound microscope : (i) Acompound microscope consists of a metal tube fitted with two convex lenses at the two ends. These lenses are called the objective lens ( the lens directed towards the object ) and the eyepiece ( the lens directed towards the eye ). Both the lenses are small in size , but the cross section of the objective lens has a short focal length . the focal length of the eyepiece is more than that of the objective lens . (ii) The metal tube is mounted on a stand . thr principal axes of the objective lens and the eyepiece are along the same line . The distance between the object and objective lens can be changed with a screw . It is possible to change the distance between the objective lens and the eyepiece. Working : (i) The object to be observed is illuminated and placed in front of the objective lens. slightly beyond the focal length of the objective lens. it's real , inverted and enlarged image is formed by the objective lens on the other side. (ii) This intermediate image lies with in the focal length of the eyepiece. It serves as an object for the eyepiece. The eyepiece works as a simple microscope . the final image is virtual, highly enlarged and inverted with respect to the original object . It can be formed at the minimum distance of distinct vision from the eyepiece . The final image is observed by keeping the eye close to the eyepiece. Use: This microscope is used to observe blood cells , microorganisms , etc. In a compound microscope , which lens has greater focal length ?