A astronomical telescope has objective and eyepiece of focal lengths 40 cm and 4 cm respectively. To view an object 200 cm away from the objective, the lenses must be separated by a distance

fo = 40cm ; fe = 4cm ; u0 = 200cm1f0=1v0-1u0 ; V0=50 cm ; L=V0+fe= 50 + 4 = 54cmwhen image is formed at least distance of distinct vision1fe=1ve-1ue ; LD=V0+ue   Ve=-25 cm 1fe=1ve-1ue ; ue=10029   LD=50+10029=53.44 cm