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.

Options

A. 8.5 cm
B. 9.5 cm
C. 10.5 cm
D. 7.5 cm

Answer

A

Explanation

`f_0 = 1 cm " " f_e = 2.5 cm`
`u_0 = -1.2 cm " " L = ?`
`1/(v_0) = 1/(f_0) + 1/(u_0) implies 1/(v_0) = 1/2 - 1/1.2`
`1/(v_0) = (0.2)/(1.2) implies v_0 = 6 cm`
`therefore L = v_0 - f_e implies L = 6 + 25 = 8.5 cm`
`L = 8.5 cm`