The length of a telescope is 2.20 m and the focal length of the eyepiece is 1.9 cm. What is the focal length of the objective lens?
A) 45 cm
B) 111 cm
C) 41 cm
D) 16 cm
E) 218 cm

Question

Quizplus · Accepted Answer

The focal length of the telescope (F) is the sum of the focal lengths of the objective lens (F_o) and the eyepiece (F_e). Given that the length of the telescope is 2.20 m (or 220 cm) and the focal length of the eyepiece is 1.9 cm, the focal length of the objective lens can be found by subtracting the focal length of the eyepiece from the total length of the telescope: F_o = F - F_e = 220 cm - 1.9 cm = 218.1 cm, which is approximately 218 cm.

The Length of a Telescope Is 2