Question

A concave lens has focal length of 14 cm . At what distance should the object from the be placed so that it forms and image at 10 cm from the lens? Also,find the magnification produced by the lens

Answer 1

f=-14cm
distance of the image (v)= 10cm
distance of the object(u)=?
magnification(M)=?


1/f = 1/v-1/u
1/-14=1/10-1/u
-1/u=1/-14-1/10
-1/u=10/-140-14/140
-1/u=-(10/140+14/140)
1/u=10+14/140
1/u=24/140
1/u=12/70
1/u=6/35
6u=35
u=35/6
u=5.833...
u=5.82cm


magnification(M)=v/u
=10/5.82
=0.58cm