The  image  obtained  with a convex  lens is erect and its  length is 4 times the length of the object.  If the  focal length  of the  lens is 20 cm, calculate  the object and image  distance

Asked by sisugsgsgsysyhshz | 9th Jun, 2017, 01:18: PM

Expert Answer:

begin mathsize 12px style Given space that
straight f space equals space 20 space cm
Magnification space straight m space equals space straight v over straight u space equals space 4
rightwards arrow straight v space equals space 4 straight u
Using space the space lens space formula comma
1 over straight f space equals space 1 over straight v space minus space 1 over straight u
1 over 20 space equals space fraction numerator 1 over denominator 4 straight u end fraction space minus space 1 over straight u
1 over 20 space equals space fraction numerator 1 space minus space 4 over denominator 4 straight u end fraction
or space 4 straight u space equals space minus space 60
therefore space straight u space equals space minus 15 space cm
rightwards arrow straight v space equals space 4 straight u space equals space space minus 60 space cm
end style

Answered by Yashvanti Jain | 9th Jun, 2017, 02:42: PM

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