Question

an object of height 1.2 is placed before a concave mirror of focal length 20cm so that a real image is formed at the distance of the 60 CM before its 5 find the position of object what will be height of image formed

Answer 1

v=60
f=-20
therefore now by using formula 1/v+1/u=1/f
1/60+1/u=1/-20
1/u=-1/20-1/60
u=-15
.
now
-v/u=h2/h1
-60/-15=h2/120
h2=4.8.
so position of object is 15cm and height of image is 4.8
u r question is not clear because you left to write CM or meter after 1.2
if my answer is helpful for you then please mark as brain list

Answer 2

Answer:

u = 30 cm

$\display \text{h _i = 2.4 cm}$

Explanation:

We have given :

Focal length = 20 cm

Image distance =  60 cm

We have to find object distance .

We know :

1 / f = 1 / v + 1 / u

Since image formed is real :

f = - 20 cm and v = - 60 cm

1 / u = 1 - 3 / 60

u = - 30 cm

Hence object distance is 30 cm .

Also given object height = 1.2 cm

We know :

h_i / h_o = - v / u

h_i / 1.2 = - 60 / 20

h_i = - 2.4 cm

Hence image height is 2.4 cm .