Question

an object is placed in front of a concave mirror of focal length 20cm three times the size of the object calculate the distance of the object from the mirror

Answer 1

hello

The mirror formula is

1/f = (1/v) + (1/u)    ............. (1)

Given

f = focal length = -20cm

v = image distance

u = object distance

we will assume that the following is given

hi = image height

ho = object height

hi = 3ho

Now,

from formula

hi / ho = -v/u = 3

we get,

v = -3u

so, using this in eq. (1), we get

-1/20 = -1/3u + 1/u

or

-1/20 = 2 / 3u

or

u = -13.33 cm

Thus, the object is distance / position of the object will be

u = -13.33 cm

I hope helps you
thanks for questioning
#be brainly