Question

if an object is placed at 20 cm infront of a concave mirror object size 2 cm and image size 2 cm then find focal length find fastly....

Answer 1

x=20

f=15

h=3

y, H = ?

Mirror equation:

1/f=1/x+1/y

1/y=(x-f)/(xf)

y=(xf)/(x-f)=(20*15)/(20–15)=60

size of the image

equation:

size=y/x=H/h

H=(yh)/x=(60*3)/20=9

Response:

position of the image is 60 cm

size of the image is 9 cm