Telescopes

Question 1

What is magnification?

Answer 1

Focal length of objective/focal length of eyepiece

Question 2

What is focal ratio?

Answer 2

Focal length of objective/objective aperture

Question 3

What are the defects with using our eyes as telescopes?

Answer 3

•very small aperture(diameter of lens)
•cannot integrate the signals received

Question 4

How is energy recieved per unit time calculated?

Answer 4

Brightness/flux

Question 5

What problem can compound lens solve?

Answer 5

Chromatic aberration

Question 6

What are faults with compound lens?

Answer 6

Heavy and absorb a lot of light

Question 7

What do newton replace refractors with?

Answer 7

Curved mirror

Question 8

What was the issue with spherical mirrors?

Answer 8

Do not bring all the light to a single focus (spherical aberration)

Question 9

How was spherical aberration solved?

Answer 9

Parabolic mirrors

Question 10

What are all telescopes today?

Answer 10

Reflectors

Question 11

What do modern day telescope designs permit?

Answer 11

Cassegrain focus design allows more compact telescopes

Question 12

Why can large telescopes produce sharper images?

Answer 12

Diffraction

Question 13

What is resolution limited by?

Answer 13

The atmosphere

Question 14

What are ways to beat the atmosphere?

Answer 14

Adaptive optics and putting telescope above atmosphere

Question 15

What is adaptive optics?

Answer 15

Moving telescope to follow the star then the seeing disk would be reduced to a point

Question 16

What is seeing?

Answer 16

The blurring of the image of a star due to turbulence in the earth’s atmosphere

Question 17

How can we improve resolution?

Answer 17

Using multiple telescopes together

Question 18

What are interferometers limited by?

Answer 18

The distance between the telescopes rather than the individual telescopes aperture

Question 19

What rays must be observed from space?

Answer 19

Uv, xray, gamma