A concave lens has a focal length of 15 cm. At what distance should an object from the lens be placed so that it forms an image at 10 cm from the lens? Also find the magnification of the lens.
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focal length =f=-15 cm after sign convention
image distance=v=-10cm
object distance=u=?
by lens formula:
1/f=1/v-1/u
1/u=1/v-1/f
= -1/10+1/15
= -3+2/30
=-1/30
u=-30cm
Magnification=m=v/u
=10/30= 1/3=0.33
image distance=v=-10cm
object distance=u=?
by lens formula:
1/f=1/v-1/u
1/u=1/v-1/f
= -1/10+1/15
= -3+2/30
=-1/30
u=-30cm
Magnification=m=v/u
=10/30= 1/3=0.33
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