Question

82. A luminous object is placed at a distance
of 40 cm from a converging lens of focal
length 25 cm. The image obtained in
the screen is
(a) erect and magnified
(b) erect and smaller
(c) inverted and magnified
(d) inverted and smaller​

Answer 1

Answer:

focal length,f=25cm

object distance from mirror=40cm

center of curvature=2f=50cm

this means object is between f and 2f

that's why

i) real

ii) inverted

iii)magnified

iv) magnification,m>-1

Answer 2

The image obtained in  the screen is (c) inverted and magnified.

Explanation:

• Focus is a point on principal axis where rays parallel to principal axis and coming from infinity converge or diverge.
• Focal length of spherical lens is half of the radius of curvature.  
• Convex lens is a converging lens. It possesses at least one surface that is curved outwards. It is thinner at its edges than at its centre.
• Focal length of the lens is $25 cm$.

• Radius of curvature for the convex lens is $2*25=50 cm$
• The position of object is at $40 cm$ which is between focus and radius of curvature.
• So, the image is formed between infinity and radius of curvature on the other side of the lens.
• So, the screen is has to be between infinity and radius of curvature.
• Image formed is real, inverted and magnified.