Determine the focal length of the objective.

Define the following :(i) Focal length.(ii) Principal focus

An object 50 cm tall is placed on the principal axis of a convex lens. Its 20 cm tall image is formed on the screen placed at a distance of 10 cm from the lens. Calculate the focal length of the lens upto two places of decimal.

An object is placed 65.7 cm from a converging lens that has a focal length of 24.6 cm. Determine the image distance. Enter a – answer if appropriate.Image DistancecmInfoAttempts: 0/∞SubmitDetermine the magnification of this image. Enter a – answer if appropriate.

Define the focal length of a lens.The distance to the furthest object that can be seen through itThe minimum thicknessThe distance from the focal point to the centre of the lensIts distance from an observer's eye

An optical device has been given to a student and he determines its focal length by focusing the image of a sun on a screen placed 24 cm from the device on the same side of the sun.(a) Name the optical device(b) Find its focal length