Refraction Of L...

A convex lens when placed in the first position forms a real image of an object on a fixed screen. The distance between the object and the screen is 75 cm. On displacing the lens from first position by 25 cm to the second position, again a real image is formed on the screen. Then the focal length of the lens is

A lens is placed between a source of light and a wall. It forms images of area A₁ and A₂ on the wall for its two different positions. The area of the source of light is

A convex lens of power 4D is kept in contact with a concave lens of power 3D, the effective power of combination will be

The power of a plano-convex lens is P. If this lens is cut longitudinally along its principal axis into two equal parts and then they are joined as given in the figure. The power of combination will be :

The plane face of a plano convex lens is silvered. If μ be the refractive index and R, the radius of curvature of curved surface, then system will behave like a concave mirror of curvature.

A slide projector lens has a focal length 10 cm. It throws an image of a 2cm × 2 cm slide on a screen 5 m from the lens. Find the size of the picture on the screen.

If the focal length of a magnifier is 5 cm calculate the power of the lens

In the above question, find the magnifying power of the lens for relaxed and strained eye.

A 35 mm film is to be projected on a 20 m wide screen situated at a distance of 40 m from the film-projector. Calculate the focal length of projection lens.

In a compound microscope the objective and the eye- piece have focal lengths of 0.95 cm and 5 cm respectively, and are kept at a distance of 20 cm. The last image is formed at a distance of 25 cm from the eye- piece. Calculate the total magnification.