A telescope has an objective lens of focal length 200 ~cm and an eye piece with focal length 2 ~cm . If this telescope is used to see a 50 meter tall building at a distance of 2 ~km , what is the height of the image of the building formed by the objective lens?

Step-by-step solution

From the formula for convex lens, aligned & 1 v - 1 u = 1 f & v= f u u-f = 200 200 10^3 [200 10^3-200 ] = 200 10^3 999 . aligned Also, magnification, aligned m & = | v u |= | I O | & = 200 10^3 999 200 10^3 = I 50 100 I & = 5000 999 5 ~cm . aligned