Question

(a) What type of lens is used as a magnifying glass?
(b) What type of lens is used to correct the defect of vision called myopia?
​(c) A convex lens has a focal length of 10.5 cm. Where should an object be placed in front of this convex lens so as to obtain an image which is real, inverted and same size as the object?

Answer 1

(a) A convex lens that is used to produce a magnified image of an object in a magnifying glass (called a hand lens in laboratory contexts).

(b) A concave lens (minus powered) is used to correct the defect of a myopic eye.

(c) A convex lens forms a real image of the same size and inverted in nature when the object is placed at point '2f' of the convex lens.

The focal length of the given lens = 10.5 cm

Hence, the object should be placed 21 cm away from the pole to form the required image.