Please inlude ALL mathematical & conceptual steps soI can understand. Thanks. A

Question

Please inlude ALL mathematical & conceptual steps soI can understand. Thanks.
A biconvex lens has a focal length of 0.20 m. Where on thelens axis should an object be placed in order to get thefollowing?

(a) a real, enlarged image with a magnification of1.5
cm
(b) a virtual, enlarged image with a magnification of 2.5
cm

Please inlude ALL mathematical & conceptual steps soI can understand. Thanks.
A biconvex lens has a focal length of 0.20 m. Where on thelens axis should an object be placed in order to get thefollowing?

Explanation / Answer

You have not entioned which sign convention touse. I shall use Real +ve; virtual -ve. So, f = +0.20 m (a) Magnification, m = +1.5 Using 1/v + 1/u = 1/f Multiplying by u throughout,          u/v + 1 = u/f      Using m = v/u           1/m + 1= u/f      u = f(1 + 1/m) = 0.20(1 +1/1.5)         = 0.20x2.5/1.5 =1/3 = 0.333 m = 33.3 cm The object is placed between F and Cof the lens.         2f>u.>f (b) Given m = -2.5     u = f(1 + 1/m) =0.20(1 - 1/2.5)          =0.20x1.5/2.5 = 0.3/2.5           =1.2/10 = 0.12 m = 12 cm The object is placed between F and the lens.              u<f.         

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