Lesson: Telescopes

In this lesson, we will learn how to calculate the imaging properties of reflecting, refracting, and compound optical systems used in telescopes.

Sample Question Videos

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Worksheet: 8 Questions • 2 Videos

Q1:

Two stars that are km apart are viewed by a telescope and found to be separated by an angle of radians . If the eyepiece of the telescope has a focal length of 1.5 cm and the objective has a focal length of 3 meters, how far away are the stars from the observer?

Q2:

What is the minimum angular spread of the beam produced?

Neglecting atmospheric effects, find the size of the spot this beam would make on the Moon. Use a value of m for the distance to the Moon.

Q3:

In a reflecting telescope, the objective is a concave mirror of radius of curvature 4.0 m and the eyepiece is a convex lens of focal length 6.0 cm. Find the apparent size of a 5.0 m tree at 20 km that you would perceive when looking through the telescope.

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