Question

A pin which is 2 cm long is placed at a distance of 16 cm from a convex lens. Assuming it to be perpendicular to the principal axis. Find the position ,size and nature of the image if the focal length of the lens is 12cm.​

Answer 1

Given:-

• Object Distance (u) = -16cm

• Focal length (f) = +12cm

• Object height (ho) = 2cm

To Find:-

• The Position, Size and the nature of image.

Solution:-

By using Lens Formula

⟹ 1/v - 1/u =1/f

Put the value , we get

⟹ 1/v =1/u + 1/f

⟹ 1/v = 1/(-16) + 1/12

⟹ 1/v = 1/48

⟹ v = +48cm

here positive sign show the image formed is real.

Now,

Magnification

⟹ m = v/u

Put the value we get

⟹ m = 48/(-16)

⟹ m = -3

⟹ he/ho = -3

⟹ he = -3×ho

⟹ he = -3×2

⟹ he = -6cm.

∴ The image is inverted and real and is 6 cm in size.

Answer 2

Explanation:

Given : . Object Distance ( u ) = -16cm Focal length ( f ) = + 12cm . Object height ( ho ) = 2cm To Find : The Position , Size and the nature ofof image . Solution : By using Lens Formula 1 / v - 1 / u = 1 / f Put the value , we get 1 / v = 1 / u + 1 / f 1 / v = 1 / ( - 16 ) + 1/12 1 / v = 1/48 = y = + 48cm here positive sign show the image formed is real . Now , Magnification m = vlu Put the value we get= m = 48 / ( - 16 ) = m = -3 he / ho = -3 he = -3xho = he = -3x2 he = -6cm . :: The image is inverted and real and is 6 cm in size .