We cannot clearly see an object kept at a distance less than 25 cm from the eye.

When a convex lens of 2.5 cm focal length is used as a magnifying glass, normal eye can see an object clearly at a distance of 25 cm. The magnifying power of the instrument is

A lens with a focal length of 25 cm produces real image of an object at a distance of 50 cm from the lens. At what distance the object placed from the lens?

A telescope using an eye piece of focal length 2 cm has a magnification 20 in normal adjustment. If the telescope is now used to view an object placed at a distance of 2 m from the objective, the new length of the telescope is (assume final image is at infinity).

A telescope using an eye piece of focal length 3 cm has a magnification 10 in normal adjustment. If the telescope is now used to view an object placed at a distance of 180 cm from the objective, the new length of the telescope is (assume final image is at infinity).

Rajashree wants to get an inverted image of height 5 cm of an object kept at a distance of 30 cm from a concave mirror. The focal length of the mirror is 10 cm. At what distance from the mirror should she place the screen ? What will be the type of the image, and what is the height of the object?

Give scientific reasons: If we bring an object closer than 25 cm from the eyes, why can we not see it clearly even though it subtends a bigger angle at the eye?

A norml eye is unable to see objects at a distance less than distance of distinct vision. If is because

Try this. i. Try to read a book keeping it very far from your eyes. ii. Try to read a book keeping it very close to your eyes. iii. Try to read a book keeping it at a distance of 25 cm from your eyes. At which time you see the alphabets clearly? Why?

An object is kept at a distance of 60 cm in front of a convex lens. Its real and inverted image is fonned at a distance of 20 cm from the lens. Find the focal length of the lens.

An object is at a distance of 10 cm from a concave mirror and the image of the object is at a distance of 30 cm from the mirror on the same side as that of the object. The radius of curvature of the concave mirror is