In a compound microscope the focal length of objective lens is 1.2 ~cm and focal length of eye piece is 3.0 ~cm . When object is kept at 1.25 ~cm in front of objective, final image is formed at infinity. Magnifying power of the compound microscope should be:

Step-by-step solution

Given : f₀=1.2 ~cm ; f_e=3.0 ~cm u₀=1.25 ~cm ; M_ = ? From 1 f₀ = 1 v₀ - 1 u₀ 1 1.2 = 1 v₀ - 1 (-1.25) aligned & 1 v₀ = 1 1.2 - 1 1.25 & v₀=30 ~cm aligned Magnification at infinity, aligned &M_ =- v₀ u₀ D f_e &= 30 1.25 25 3 ( D=25 ~cm least distance aligned of distinct vision) =200 Hence the magnifying power of the compound microscope is 200