A simple refracting telescope has an objective of focal length 75 cm and an eyepiece of focal length 3.0 cm.When viewed by the naked eye,the moon subtends an angle of about 0.009 radians.What angle is subtended by the moon when it is viewed through this telescope? A)0.022 rad B)0.22 rad C)3.6 $\times$ 10^-4 rad D)0.078 rad E)3.0 $\times$ 10^-3 rad

Question

A simple refracting telescope has an objective of focal length 75 cm and an eyepiece of focal length 3.0 cm.When viewed by the naked eye,the moon subtends an angle of about 0.009 radians.What angle is subtended by the moon when it is viewed through this telescope? A)0.022 rad B)0.22 rad C)3.6 $\times$ 10^-4 rad D)0.078 rad E)3.0 $\times$ 10^-3 rad

Quizplus · Accepted Answer

The angular magnification of a telescope is given by the ratio of the focal length of the objective lens to that of the eyepiece. Thus, magnification = $ \frac{75}{3} = 25 $. The angle subtended by the moon when viewed through the telescope is $ 0.009 \times 25 = 0.225 $ radians, which is approximately $ 0.22 $ radians.

A Simple Refracting Telescope Has an Objective of Focal Length ×\times×

A Simple Refracting Telescope Has an Objective of Focal Length $\times$