The image of a small electric bulb fixed on the wall of a room is to be obtained on the opposite wall 3m away by means of a large convex lens. What is the maximum possible focal length of the lens required for the purpose?

A bulb is located on a wll.Its image of equal size is to be obtained on a parallel wall with the help of a convex lens .The lens is placed at a distance d ahead of second wall.Then the required focal length will be

A convex lens is used to obtain a magnified image of an object on a screen 10 m from the lens .If the magnification is 19,find the foal length of the lens.

An object is placed at a distance of 1.5 m from a screen and a convex lens is interosed between them .the magnification produced is 4.What is the focal length of the lens?

An object is 2m away from a lens. Which forms an erect image 1/4th the size of the object, determine the focal length of the lens.What type of the lens is this?

Find the radius of curvature of the convex surface of a plano convex lens,whose focal length is 0.3 m and the refractive index of the material of the lens is 1.5/

A ocnverging bem of light forms of a sharp image on a screen. lens is placed in the path of the beam at 10 cm from the screen.It si found that screen has to be moved 8 cm further away from the lens to obtain a sharp image.Find the focal length and natrue of the lens.

A convex lens is placed in contact with a plane mirror.A point object at a distance of 20 cm on the axis f this combinatin has its image coinciding with itself.What is the focal length of the lens?

A double convex lens has 10 cm and 15 cm as its two radii of curvature.The image of an object,placed 30 cm from the lens,is formed at 20 cm from the lens on the other side.Find the refractive index of the material of the lens.Whgat will be the focal length ?What will be the focal length of the lens,if it is immersed in water of refractive index 1.33?

At what distance should be placed from a convex lens of focal length 15 cm to obtain an image three times the size of the object?

What do you mean by a lens? What are concave and convex lenses? What do you mean by Prnicipal axis, Optical centre and Principal focus and focal length of a lens?