An object of size 7 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed, so that a sharp focused image can be obtained ? Find the size and the nature of the image.
Mirror formula : 1v+1u=1f...........(1)
So, u=−27cm
Concave mirror have negative focal length.
f=−18cm
Putting the values in (1),
1v+1−27=1−18
We get , v=−54cm
Also,
Magnification = h2h1=−vu
h27.0=−−54−27
h2=−14.0cm
Image will be real and inverted and will be of size 14 cm.