🔭W5 L1 - The nature of light - detection with telescopes

Question 1

What velocity is needed to orbit planet Earth?

Answer 1

7,300 metres per second

Question 2

What is the escape velocity for Earth?

Answer 2

11.2 km per second

Question 3

What is the diameter limit of a lens for a refractor telescope?

Answer 3

1 metre

Question 4

What’s the largest you can build a reflecting mirror?

Answer 4

8 metres

Question 5

How accurate do mirrors need to be?

Answer 5

Nanometre level ie 10⁻⁹ metres (10 nanometres)

Question 6

What’s the diameter of the James Webb Space Telescope primary mirror?

Answer 6

6 metres

Question 7

What’s the diameter of the ELT primary mirror?

Answer 7

39 metres

Question 8

What’s the diameter of the pupil of the human eye (on average at night)?

Answer 8

5 millimetres

Question 9

What’s the formula for area of a circle?

Answer 9

Pi r squared

A = 𝝅.r²

Question 10

What’s the collecting area ratio of the ELT mirror to the human pupil?

Answer 10

60 million

Question 11

How much fainter objects can ELT see compared with the human eye?

Answer 11

36 million times fainter

Question 12

What’s the speed of light in a vacuum?

Answer 12

3 x 10⁸ m/s

Question 13

What is the colour of light (for a human) determined by?

Answer 13

It’s frequency/wavelength

Question 14

What is the energy of a photon related to?

Answer 14

It’s frequency/wavelength

Question 15

State 5 properties of light

Answer 15

1) vacuum speed is 3.10^8m/s 2) colour p wavelength/f 3) E det by wavelength/f 4) wave particle duality 5) bends enter/exit materials (VW3b)

Question 16

What’s a mnemonic for the EM spectrum?

Answer 16

Ronald McDonald Invented Very Useful X-ray Goggles

Question 17

What wavelength range does the human eye perceive?

Answer 17

380-750nM

Question 18

Shorter wavelengths are perceived by humans as:

Answer 18

Bluer

Question 19

Longer wavelengths are perceived by humans as:

Answer 19

Redder

Question 20

The wavelength of gamma rays and x-rays is:

Answer 20

Short

Question 21

The wavelength of infrared, microwave, radio is:

Answer 21

Long

Question 22

Which 3 wave types are detected in high energy processes?

Answer 22

Gamma rays, x-rays, ultraviolet

Question 23

Name 3 things that observations focused on gamma-rays, x-rays, and UV can detect

Answer 23

Supernovae, pulsars, black holes

Question 24

Name 2 things in space that can be detected using infra-red and microwave wavelengths?

Answer 24

1) dust 2) warm objects

Question 25

Name 2 things radio waves are useful for studying in space

Answer 25

1) Hydrogen, 2) magnetic fields of galaxies

Question 26

What does UV, XR and gamma ray astronomy show is at the centre of the Crab Nebula?

Answer 26

A pulsar

Question 27

Which retinal cells detect intensity in the eye?

Answer 27

Rods

Question 28

Which retinal cells detect colour?

Answer 28

Cones

Question 29

Which cells are more numerous in the human eye?

Answer 29

Rods

Question 30

What are 6 advantages of photographic plates vs the human eye?

Answer 30

Finder.SCOPE

1) Filterable, 2) Sensitivity higher, 3) Colour, 4) Objective, 5) Permanent, 6) Exposure longer

Question 31

Which 2 wavebands does the atmosphere most allow through?

Answer 31

1) visible, 2) radio