Question

A convex lens forms a real and inverted image of an object at a distance of 100 cm

from it. Where is the object placed in front of the lens if the image is equal to the size of

the object? Also find the power of the lens.

anyone plss i am giving 20 points​

Answer 1

(i) In this case needle is the object. Since the image is real, inverted and of same size as the needle (or object), the needle must be at the same distance (50 cm) in front of lens, as the image is behind the lens. Thus, the needle is placed at a distance of 50 cm from lens in the front.

(ii) When the image formed by a convex lens is of the same size as the needle (or object), then the distance of needle from the lens is 2f (twice the focal length).

In this case: focal length, f = 50/2cm

Thus, the focal length of this convex lens is +25 cm. This is equal to (+25)/100m or +0.25m. Now, Power, P= 1/(f(in meters)) = 1/(+0.25) = +4.0 D

So, the power of this convex lens is +4.0 diopters.

Answer 2

Answer:

convex lens is used for old men and women because they didn't have good sight so they use convex lens to see