Question

22. How far should an object be placed from the pole of a converging mirror of focal
length 20 cm to form a real image of the size exactly 1/4 th the size of the object?​

Answer 1

Answer:

to get the image of same size as that of of object tham the object should placed on the centre of curvature whose distance is twice or double the focal length of the mirror

Explanation:

i.e; object should be placed at 40 cm to get the image of same length

hope it helps u

so plz follow and mark me as a brainliest and also thnxs to my answer

Answer 2

Answer:

   u = -100cm

Explanation:

focal length (f) = -20cm

Magnification (M) = 1 / 4

image distance (v) = v

object distance (u) = u

M = -v / u

Here magnification is negative because it forms a real image

This is because virtual image formed by concave mirror is enlarged whereas according to the question the image is diminished and hence it forms a real image

-(1 / 4) = -v / u

1 / 4 = v / u

u = 4v -------{i}

1 / v + 1 / u = 1 / f

1 / v + 1 / 4v = - 1 / 20

4 / 4v + 1 / 4v = -1 / 20

5 / 4v = -1 / 20

4v = -100

v = -25cm

u = 4v = -100cm

∴ The object should be placed 100 cm to the left of the mirror.