Astrophysics

Question 1

Principal focus

Answer 1

Where rays meet

Question 2

Focal length

Answer 2

Distance between lens axis and principal focus

Question 3

Power equation

Answer 3

Power = 1/ focal length

Question 4

Real image

Answer 4

Image that can be projected

Question 5

Magnification

Answer 5

How many time’s it has been enlarged

Question 6

Problems with refracting telescopes

Answer 6

Spherical aberration: not all rays focus at the same point

Chromatic aberration: different frequencies refract by different amounts

Question 7

Angular resolution

Answer 7

Smallest angle the telescope is able to detect and analyse

Question 8

Rayleigh criterion

Answer 8

To be able to resolve 2 stars they need to be separated by more than the radius of the airy disk

Question 9

Quantum efficiency

Answer 9

N.o. Of electrons detected/ n.o. Detected

Question 10

Collecting power

Answer 10

How much light it can gather

Pid^2/4

Question 11

AU

Answer 11

The mean distance between the earth and sun

Question 12

Light year

Answer 12

Distance that light can travel in a year

Question 13

Parsec

Answer 13

The distance to a nearby star when the angle subtended is 1 arcsecond

Question 14

Apparent magnitude

Answer 14

How bright the star appears to be from Earth

Question 15

Absolute magnitude

Answer 15

The brightness of a star from 10pc

Question 16

Black body

Answer 16

Absorbs the same energy it emits

Question 17

Plasma

Answer 17

Ionised gas

Question 18

Spectral class O

Answer 18

Blue

25000-50000

Question 19

Class B

Answer 19

Blue

11000-25000

Question 20

Class A

Answer 20

Blue-white

7500-11000

Question 21

Class F

Answer 21

White

6000-7500

Question 22

Class G

Answer 22

White-yellow

5000-6000

Question 23

Class K

Answer 23

Orange

3500-5000

Question 24

Class M

Answer 24

<3500

Question 25

Nuclear fusion

Answer 25

The joining of 2 small nuclei to make a larger nucleus

Question 26

Neutron star

Answer 26

A star with a same density as a nucleus

Question 27

Electron degeneration

Answer 27

P+e->n+v

Question 28

Supernova

Answer 28

Rapid increase in magnitude followed by a drop in magnitude

Question 29

Black hole

Answer 29

An object who’s escape velocity is greater than the speed of light

Question 30

Event horizon

Answer 30

The distance between the black hole and the point where the escape velocity is equal to the speed of light

Question 31

Shwartzschild radius

Answer 31

The distance from the black hole to the event horizon

Question 32

Binary system

Answer 32

2 stars orbiting a common centre of gravity

Question 33

Standard candle

Answer 33

An object who’s magnitude is known

Question 34

Doppler shift

Answer 34

The perceived change in wavelength and frequency of a sound wave moving relative to the observer

Question 35

Redshift

Answer 35

Frequency deceasing and wavelength increasing of light as an object moves away

Question 36

Blueshift

Answer 36

Light wave deceasing in wavelength and increasing in frequency as the object moves towards us

Question 37

Evidence for the Big Bang

Answer 37

CMBR

Relative abundance of hydrogen

Question 38

The Big Crunch

Answer 38

Gravity pulling the universe back on itself to a singularity

Question 39

The big rip

Answer 39

All matter ripped apart

Question 40

Dark matter

Answer 40

The matter of the universe we can’t see that attempts to stop the expansion of the universe

Question 41

Dark energy

Answer 41

Causes the universe to expand at an increasing rate

Question 42

Quasars

Answer 42

Active galactic nuclei consisting of a supermassive black hole, accretion disk of dust and matter, and lobes emitting x-rays

Question 43

Exoplanets

Answer 43

Planets orbiting a sun that is not our own

Question 44

The 3 methods of detecting exoplanets

Answer 44

Direct imaging
Transit observations
Variation in Doppler shift