Question

An object 5.0 cm in length is placed at a distance of 20 cm in front of a convex lens of radius of curvature 30 cm. Find the position of the image, its nature and size.

Answer 1

Answer:

Then object will be placed between focus and center of curvature

nature of the image real ,enlarged, inverted

and beyond centre of curvature

Answer 2

Answer:

Image is virtual and erect and formed behind the mirror.

Size of image is 2.2 cm.

Explanation:

Here it is given that the lens is convex. Then,

Radius of curvature (R) = 30 cm

f = R/2 = 30/2 = 15 cm

Hence, focal length of lens = f = 15 cm

Distance of object, u = -20 cm,

Height of object, h = 5 cm.

By lens formula, we know that,

1/v +1/u = 1/f

=> 1/v = 1/f - 1/u

By applying values, we get,

1/v = 1/15+ 1/20 = 7/60

v = 60/7 = 8.6 cm.

Image is virtual and erect and formed behind the mirror.

hi/ho = v/u

hi/5 = 8.6/20

hi = 2.2 cm.

Size of image is 2.2 cm.