Large Diameter Telescopes

One radian is subtended when the length travelled along the circumference of the circle is?

What is 5π/6 radians in degrees?

• 180
• 150
• 360
• 120

Tags

CCSS.HSF.TF.A.2

What is 240 degrees in radians? 

• π/3
• 4π/3
• 5π/3
• 2π/3

Tags

CCSS.HSF.TF.A.1

What is 2π/3 radians in degrees? 

• 150
• 120
• 180
•  30

Tags

CCSS.HSF.TF.A.1

What is 225  degrees in radians? 

• 7π/4
• 5π/4
• 3π/4
• 5π/3

Tags

CCSS.HSF.TF.A.2

The Griffith Observatory in Los Angeles includes an astronomical refracting telescope (Griffith telescope) with an objective lens of diameter 305 mm and focal length 5.03 m. Calculate the wavelength of light for which the Griffith telescope has a minimum angular resolution of 1.8 × 10–6 rad

• 5.5 × 10–7 m

• 8.5 × 10–7

• 4.5 × 10–7 m

• 6.5 x 10-7 m

• 7.5 × 10–7 m

The Griffith telescope is used to observe two point objects which subtend an angle of 1.8 × 10–6 rad at the unaided eye.The typical human eye has a minimum angular resolution of approximately 3.2 × 10–4 rad. Calculate the focal length of the eyepiece lens so that an observer can just resolve the two objects when observing them through the Griffith telescope. Objective lens diameter is 305 mm and focal length is 5.03 m.

Astronomers investigating the supermassive black hole at the centre of the Milky Way galaxy detect radio waves at a frequency of 230 GHz. By correlating the information from several radio telescopes, they can obtain images with the same resolution as a single radio telescope with a diameter of 5000 km. Calculate the minimum angular separation which could be resolved by a radio telescope of diameter 5000 km detecting waves of frequency 230 GHz

• 2.6 × 10−8 rad

• 2.6 × 10−9 rad

• 2.6 × 10−10 rad

• 2.6 × 10−11 rad

Larger aperture diameter telescopes are desirable for two main reasons:

• Greater collecting power so images are brighter

• Greater magnification

• Better resolving power so images are clearer

• Easier to move

The Triesnecker Crater on the Moon has a diameter of 23 km. Calculate the angle subtended by the image of this crater when viewed through a telescope of angular magnification 50 on the Earth.

distance from Earth to Moon = 3.8 × 10⁵ km

• 3.026×10–3

• 3.026×10–5

• 6.053×10–3

• 6.053×10–5