Question

A compound microscope has an objective of focal length 1 cm and an eyepiece of focal length 2.5 cm. An object has to be placed at a distance of 1.2 cm away from the objective for normal adjustment. a.Find the angular magnification. b.Find the length of the microscope tube.

Answer 1

Here, `f_0 = 1 cm, f_e = 2.5 cm`.
`u_0 = -1.2 cm., m = ? L = ?`
As `(1)/(v_0)-(1)/(u_0)=(1)/(f_0)`
`:. (1)/(v_0)=(1)/(f_0)+(1)/(u_0)=(1)/(1)-(1)/(1.2)=(0.2)/(1.2)`
`v_0 = 1.2//0.2 = 6 cm`
As `m = (v_0)/(|u_0|)(1 + (d)/(f_e))`
`:. m = (6)/(1.2)(1 + (25)/(2.5)) = 55`
`L = v_0 + f_e = 6 + 2.5 = 8.5 cm`.