A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the nature, position and size of the image.

A 10 cm tall object is placed perpendicular to the principal axis of a

1.	A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 12 cm. The distance of the object from the lens is 18 cm. Find the nature, position and size of the image.
Answer» SOLUTION :As per question f = + 12 cm, u = - 18 cm and h = + 10 cm As per lens formula `(1)/(v) - (1)/(u) = (1)/(f)`, we have `(1)/(v) = (1)/(u) + (1)/(f) = (1)/((-18)) + (1)/((+12)) = (1)/(36) rArr v = + 36` cm The image is formed on opposite side of lens at a distance of 36 cm from it. The image is a real and inverted image. MOREOVER, magnification `m = (h.)/(h) = (v)/(u)` `rArr` Size of image `h. = (v)/(u) xx h = ((+36))/((-18)) xx (+10) = - 20` cm So, the size of image is 20 cm tall and is formed below the principal axis.