Question

an object is kept at 40cm in front of concave mirror of focal length 20 cm. Find image distance, nature

Answer 1

The image of infinity and if its at 2f the image will come to 2f using the mirror relation with the1/v + 1/u = 1/f

So 1/v = 1/f - 1/u , = 1/15 - 1/20

5/(15x20)= 1/60 therefore v= 60 cm

So the image will be formed at 60 cm

With magnification m= v/u

                                  = 60/20 = 3

therefore, the image will be 3 times larger and nature of the image will be real and inverted.

hope it helps you friend

Answer 2

$\huge\red{Answer }$

We will use the mirror formula.

1/f = 1/u + 1/v

f = 20 cm

v = 40 cm

1/20 = 1/u + 1/40

1/u = 1/20 - 1/40

1/u = (2 - 1) / 40

1/u = 1/40

The image distance is 40 cm

Since the image position is positive the image is real.

HOPE IT HELPS YOU !!