# Worksheet: Telescopes

In this worksheet, we will practice calculating the imaging properties of reflecting, refracting, and compound optical systems used in telescopes.

Q1:

What is the angular magnification of a telescope that has a 100 cm focal length objective and a 2.50 cm focal length eyepiece?

• Ax
• Bx
• Cx
• Dx
• Ex

Q2:

A 7.5x pair of binoculars produces an angular magnification of , acting like a telescope (where mirrors are used to make the image upright). If the binoculars have objective lenses with a focal length of 75.0 cm, what is the focal length of the eyepiece lenses?

• A cm
• B cm
• C cm
• D cm
• E cm

Q3:

A large reflecting telescope has an objective mirror with a radius of curvature of 10.0 m. What angular magnification does it produce when an eyepiece of focal length 3.00 m is used?

• Ax
• Bx
• Cx
• Dx
• Ex

Q4:

A planet at a distance of m from Earth is observed by a telescope that has a focal length of the eyepiece of 1 cm and a focal length of the objective of 1 cm. The planet is seen to subtend an angle of rad at the eyepiece. What is the size of the planet?

• A m
• B m
• C m
• D m
• E m

Q5:

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?

• A km
• B km
• C km
• D km
• E km

Q6:

A telescope can be used to enlarge the diameter of a laser beam and limit diffraction spreading. The laser beam is sent through the telescope in the direction opposite to the normal one and can then be projected onto a satellite or the Moon. This is done with a telescope, producing a 3.50 m diameter beam of 630 nm wavelength light.

What is the minimum angular spread of the beam produced?