the focal length of a convex lens made of glass is 20cm what will be its new focal focal length when placed in a medium of refractive index 1.25{experts plz answer this question properly, please dont give a wrong link , here only refractive index of medium is given , not the refractive index of glass and water } so please please..answer this..or explain this
 

Dear student
formula for the focal length is1f=(μlensμmedium-1)×(1R1-1R2)120=(1.5-1)×(1R1-1R2)120=(0.5)×(1R1-1R2)(1R1-1R2)=120×0.5=110...11f=(1.51.25-)×(1R1-1R2)...2putting the value of(1R1-1R2)from eqn 1 into 21f=(1.51.25-)×110=(1.5-1.25)1.25×110=150f=50cmRegards

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Lens made up of glass.read second line.so refractive index is 1.5
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the final answer ???
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