A thin converging lens of focal length f= 25 cm forms the image of an object on a screen placed at a distance of 75 cm from the lens. The screen is moved closer to the lens by a distance of 25 cm. The distance through which the object has to be shifted, so that its image on the screen in sharp again is

A concave lens of focal length 15 cm forms an image 10 cm from the lens. How far is the object placed from the lens ?

A convex lens has a focal length of 25 cm. Calculate the distance of the object from the lens if the image is to be formed on the opposite side of the lens at a distance of 75 cm from the lens. What will be nature of image ?

A microscope consists of an objective of focal length 1.9 cm and eyepiece of focal length 5 cm. The two lenses are kept at a distance of 10.5 cm. If the image is to be formed at the least distance of distinct vision, the distance at which the object is to be placed before the objective is (least distance of distinct vision is 25 cm)

An object is placed at a distance of 20 cm from a thin double convex lens of focal length 15 cm. Find the position and magnification of the image.