Question

radius of curvature of concave mirror is 40 cm and the size of image is twice that of the object then the object distance is

Answer 1

here is your answer....

remember .. this an important formula that i have used

Answer 2

Answer : 30 cm✔✔

Explaination :

Given that :

Radius of curvature of concave mirror, R = -40cm

so, focal length of concave mirror,f = -20cm

size of image is twice as that of object.

so, magnification , m = size of image/size of object

= 2/1 = 2

now, magnification , m = -v/(-u) = 2

v = 2u ......(1)

use formula, 1/v + 1/u = 1/f

or, 1/(2u) + 1/u = 1/-20 [ from equation (1) ]

or, 3/2u = 1/-20

hence, u = -30cm ✔

I hope it will help you ☺

Fóllòw Më ❤