Answers

2016-02-10T12:10:23+05:30
Focal length of the lens=f=20cm
Object - distancee= u=?
Image distance=v=15cm
object height = h_{o} =5cm
Image height= h_{i} =?
1/f=1/v-1/u
1/u=1/v-1/f
1/u=1/15-1/20
1/u=4-3/60
1/u=1/60
u=60cm
Therefore the object must be placed at a distance of 60cm from the lens
v/u= h_{i}/  h_{o}
 h_{i} =15/60*5=5/4=1.25cm


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