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For a convex lens to act as a magnifying glass, the object should be placed……………….. .

Show that a convex lens produces an N times magnified image,when the object distances from the lens have magnitude (f+- f//N) .Here,f is the magnitude of the focal length of the lens.Hene,find the two values of object distance,for which a convex lens of power 2.5 D will produce an image that is four times as large as the object.

A card sheet divided into squares each of size 1 mm^2 is being viewed at a distance of 9 cm through a magnifying glass (a converging lens of focal length 10 cm) held close to the eye. What should be the distance between the object in converging lens and the magnifying glass if the virtual image of each square in the figure is to have an area of 6.25 mm^2 . Would you be able to see the squares distinctly with your eyes very close to the magnifier ?

A convex lens of foal length 30 cm and a concave lens of focal length 60 cm are placed in contact.If the object is placed 40 cm away from the combination ,, find the position of the image.

A converging lens of focal length 6.25 cm is used as magnifying glass. If the near point of the observer is 25 cm from the eye and the lens is held close to the eye, calculate the distance of the object from the lens

A convex lens from a real and inverted image of a needle at a distance of 50 cm from it. Where is the needle be placed in front of the convex lens if the image is equal to size of the object? Also, find the power of the lens?

A concave lens has focal length of 15 cm. At what distance should the object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification produced by the lens.

The focal length of a convex lens is 30 cm and the size of image is quarter of the object.Them,the object distance is