How to derive the Lens Formula ?

Asked by tanishqa.rathod | 13th Dec, 2015, 11:30: AM

Expert Answer:


The figure above shows that formation of a real, inverted and diminished image A’B’ of the object AB placed beyond the centre of curvature at a distance u from the convex lens. Let v be the image distance. 

According to Cartesian sign convention,

Object distance (OB) = -u

Image distance (OB’) = +v

Focal length (OF1 = OF2) = +f

From geometry of figure above, right angle ΔABO and ΔA’B’O are similar.

Answered by Yashvanti Jain | 14th Dec, 2015, 10:33: AM