When an object is placed at a distance of 60 cm from a convex mirror the magnification produced is 1/2. Where should the object be placed to get a magnification of 1/3.

Given,

Object distance u1 = -60 cm


Magnification m1 = 1/2


If magnification m2 = 1/3


Then object distance u2 =???






v1 = 30 cm


We know that mirror formula is:



Substituting the given values in the formula:





So , f = 60 cm


The image must have same focal length so


Substituting the given values here:




60 v2 + 60 u2 =


60 v2 – u2v2 = -60 u2


v2 (60-u2) = -60 u2



We know that,



Substituting the above given values here:






60 – u2 = 180


– u2 = 180 – 60


– u2 = 120


u2 = -120 cm


The object should be placed at 120 cm from the mirror to get a magnification of 1/3


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