Further Physics Flashcards Preview

Physics 7 > Further Physics > Flashcards

Flashcards in Further Physics Deck (105)
Loading flashcards...
1

Solar day

So today is the time taken between successive means = 24 hours

2

Lunar eclipse

This occurs when the Moon moves into the earth shadow. The eclipses are rare because the moon orbits the Earth at the angle about 5° to the Earth's path around the sun

3

Solar eclipse

This occurs when the sun, moon and a line up so that the moon appears to block out the sun

4

Geocentric model

-ptolem = The earth at the centre of the solar system

5

Heliocentric model

- capernicus = Sun at the centre of the solar system

6

How do you planets move

Retrograde motion

7

Retrograde motion

Distant planet take longer to complete their orbits them planet is closest to the sun. Consequently, the relative position change over time
E. G. Mars

8

What is constellation

A named group of stars that form a pattern in the sky as seen from Earth although the stars themselves usually have no connection with each other

9

Why can we see more stars in the night sky in summer than winter

1. The earth has moved to the other side of its orbit around the sun.

2. Nights are longer in winter and there are some very bright lights on show.

3. In the summer months are night skies aim towards the centre of the Galaxy

10

What is the Milky Way

A band of light stretching from the north-east to the south west across the sky

11

Celestial sphere

An imaginary sphere with the earth at the centre, on which we imagine all astronomical objects are located

12

Celestial equator

The midline around the celestial sphere

13

Ecliptic

Path taken by the sun along the celestial to be in one year

14

Declination

The angle of the object above or below the celestial equator

15

Right ascension

Angle of the object along the celestial equator with the vernal equinox (point where the elliptic crosses the celestial equator) at zero

16

What is one arch minute

1/60 of a degree (1')

17

What is 1 arch second

1/3600 year of a degree (1")

18

Parallax

This is the effect whereby the position of an object appears to change when it is viewed from a moving source

19

What is the equation of the parallax angle

Parallax angle = Alpha + beta/2

20

What does the parallax angle show

The parallax angle allows us to find out the distance to stars which are close to earth

21

What is the relationship between the parallax angle and parsec

When the parallax angle is one of the second the distance is 1 parsec (pc)

22

The simple question for parsecs (pc)

Distance (in parsecs) = 1/ parallax angle (measured in arc seconds)

23

What factors affect the brightness of the star

. size
. temperature/age
. distance
. chemical composition

24

Intensity

Intensity of a source of radiation is the number of photons which fall on a surface every second

25

What are the properties of intensity

1. The radiation spreads out as it moves away from the source

2. this means that the intensity decreases with distance. In fact, it obeys the inverse square law, which means that the intensity decreases by value which is inversely proportional to its (distance)2

26

Sidereal day

It's ideal day is the time taken for the F to rotate through 360° (measured against a very distant star) = 24 hours and 56 minutes

27

Heber Curtis hypothesis

1. Heber Curtis argued for the island universe hypothesis.

2. He said that the spiral nebulae were galaxies like our own

3. he believed that our galaxy was only 30,000 ly across

4. that our sun was near the centre of it

27

Harlow Shapley hypothesis

. Harlow Shapley thought our galaxy was much bigger, 300,000 ly across, and that it formed the whole universe
. he believed that the sun was not at the centre of the galaxy
. that the spiral nebulae were just clouds of gas, relatively small and nearby

28

What did Edwin Hubble look at

1. Edwin Hubble looked at variable stars (Cepheid Variables) in the Adronema nebula 2. the cycle of brightness (period) was long, suggesting that the stars were very bright, but they appeared very dim from Earth suggesting that they were very long way away 3. this data suggests that nebulae are other galaxies and are a very long way away

30

Nebulae

Extended, cloud like, objects in space, for example galaxies or gas clouds

31

What did Henrietta Leavitt find

She found that there was a direct correlation between the brightness of a variable star and its PERIOD

32

What is the period of a star

The time it takes to complete a full cycle

33

How do we work out how far away a a star is

We can work out how far away a star or galaxy is by looking at nearby variable stars and applying the mathematical relationship between distance and velocity

34

What did Hubble's graph show

• the correlation on the graph, that is :- all the galaxies are moveing away from each other and the further apart they are, the great the speed at which they are moving (recessional velocity)

35

What does redshift tell us

The stretching of light to longer wavelengths caused by the expansion, space, or by the recessional velocity of a source

36

What is the period of a cepheid variable

Is the time taken to go through a full cycle from bright to dim

37

Heber Curtis hypothesis

1. Heber Curtis argued for the island universe hypothesis.

2. He said that the spiral nebulae were galaxies like our own

3. he believed that our galaxy was only 30,000 ly across and that our sun was near the centre of it

38

Harlow Shapley hypothesis

1. Harlow Shapley thought our galaxy was much bigger, 300,000 ly across, and that it formed the whole universe
2. he believed that the sun was not at the centre of the galaxy and that the spiral nebulae were just clouds of gas, relatively small and nearby

39

What did Henrietta Leavitt examine

Henrietta Leavit examined variable stars in the Greater and Lesser Magellanic Clouds- this meant that she knew they were all the same distance from us

40

Hubble and the Great Debate

1. Edwin Hubble looked at variable stars (Cepheid Variables) in the Adronema nebula

2. the cycle of brightness (period) was long, suggesting that the stars were very bright, but they appeared ver dim from Earth suggesting that they were very long way away

3. these data suggest that nebulae are other galaxies and are a very long way away

42

Nebulae

Extended, cloud like, objects in space, for example galaxies or gas clouds

43

What did Henrietta Leavitt find

She found that there was a direct correlation between the brightness of a variable star and its PERIOD

44

What is the period of a star

The time it takes to complete a full cycle

45

How do we work out how far away a a star is

We can work out how far away a star or galaxy is by looking at nearby variable stars and applying the mathematical relationship between distance and velocity

48

What did Henrietta Leavitt examine

Henrietta Leavit examined variable stars in the Greater and Lesser Magellanic Clouds- this meant that she knew they were all the same distance from us

49

What two pieces of information suggest the Big Bang

1. red shift
2. cosmic background radiation

50

How does redshift link with the spectrum

Objects moving away show light which appears to have shifted towards the red end of the spectrum

51

What happens when light travels from one substance to another

Refraction- when light travels from one substance (medium) to another it may change speed.
1. If the angle at which it approaches the second medium is 90° it will continue unchanged.
2. At any other angle the light may change direction.

52

Focal length

Th distance from the centre of the lens to the focal point

53

Power of lens

Power of a lens tells us how good it is at refraction light

54

Power triangle

Power= 1/ focal length (in metres)

55

What is the unit and symbol for power

Symbol : P
Unit : Dioptres

56

What do we have to remember when finding the power

ALWAYS CONVERT FOCAL LENGTH INTO DIOPTRES

57

How does refraction occur been the light is parallel to the principal axis

A ray of light which is parallel to the principal axis is refracted through the focal point

58

How does refraction occur when a ray of light passes through the the focal point

A ray of light passing through the focal point is refracted parallel to the principal axis

59

How does refraction occur when a ray of light passes through the centre of curvature

A ray of light passing through the centre of curvature continues

60

Objective lens

The (larger diameter) lens at the front of a refracting telescope

61

Eyepiece

The (smaller diameter) lens through which the observer looks when using a telescope

62

What does the objective and eyepiece lens have to be and why

1. the objective lens has a larger diameter than the eyepiece because objective needs to have a large area to collect more light and make a bright and clear image, it forms an image of the object at its focal point

63

Magnification equation

Magnification = focal length of objective lens/ focal length of eyepiece
Or fo/fe

64

Chromatic aberration

The different colours that make up white light have different wavelengths. At any lens, each colour will be refracted by a different amount. This means that images may be surrounded by a coloured 'fringe' or blurring effect

65

Name the problems with refracting telescopes

1. Chromatic aberration
2. Over time glass flows, so lenses will become distorted

66

Diffraction

1. when waves pass through a gap (aperture) which is approximately one wavelength wide they spread out in a curved path
2. this means that there maybe distortions effects at the edges of the lenses, mirrors etc.
so a large lens will show fewer diffraction effects

67

Ground state

The original energy level in an atom

68

The absorption spectrum

An absorption spectrum has BLACK LINES on it where energy is absorbed from the radiation to raise some of the electrons to higher energy levels

69

Emission spectrum

A emission spectrum has coloured lines on it where the energy that was absorbed is now released

70

What does the spectral lines show us about the universe

1. Spectral lines from other stars, and even from other galaxies are similar to that of our Sun
2. This suggests their are stars like our sun in different galaxies, elements are the same throughout the universe (the Big Bang)

71

What does the absence of certain light tell us e.g. Yellow light

There is no yellow light from this atom because only certain energy levels are allowed, so only certain colours are emitted

72

Boyle's law

If we increase the pressure on a gas it's volume decreases. This occurs if we keep the temperature constant

73

What does the boyles law mean in terms of graphs

This means that pressure is inversely proportional to volume
1. pV = constant

74

Temperature

Is the measure of heat energy (movement of the constituent ((particles that make it up )))

75

Absolute 0

Temperature at which particles have the minimum possible energy (-237 degrees centigrade)

76

What is the pressure of a gas

The pressure of a gas is a measure of the number of times the particles collide with the walls of the container every second

77

What happens to the pressure and temperature if we keep the volume of a gas constant

If we keep the volume of a gas constant we find that the pressure is directly proportional to the temperature
1. p/T = constant

78

What happens when the volume when the temperature is increased at a constant pressure

When we increase the temperature at a constant pressure, we find that, as the temperature increases the volume decreased

79

What do we always have to remember when using temperature in equations

USE KELVIN FOR TEMPERATURE NOT DEGREES CENTIGRADE
1. by adding 273 degrees centigrade

80

The birth of a star

1. A cloud of hydrogen forms in space
2. Gravitational attraction causes the particles to move together
3. The mass of particles increases its gravity as its gets bigger but also, as particles join the mass they increase its energy
4. When the inward gravitational force equals the outward force which resolute fro the particles moving around more, we say the mad is in its equilibrium
5. If some kind of change occurs, like a supernova (exploding star), then the mass may get even bigger
6. Eventually it will gain sufficient energy to glow. This is called the protostar
7. If the particles gain sufficient energy they release photons of energy as light, infra-red etc.

81

Strong nuclear force

This is the force that holds protons and neutrons together in the nucleus

82

Thermonuclear fusion

1. This force only avid over s very small range (about 10 to the minus 15) but is strong enough to overcome electrostatic repulsion between the protons
2. If particles have sufficient energy to approach close enough to the nucleus for the strong nuclear force to act on them they will fuse together and this releases energy

83

How do we find the number of neutrons

Neutrons = larger - smaller

84

How to determine which is which regarding printings, neutrons and electrons

Smaller= atomic no. Of protons
Larger = mass no. Of electrons and neutrons

85

Plasma

A state of matter where the particles have so much energy that they spectate into protons, electrons and neutrons

86

Name of hydrogen with a mass of 1,2 and 3

1. Mass of 1 : hydrogen
2. Mass of 2 : deuterium
3. Mass of 3 : tritium

87

How is deuterium formed

When two hydrogen nuclei collide at high energies they fuse to form deuterium and they lose mass so energy is released

88

What is needed to make nuclei fuse

High temperatures are needed to make nuclei fuse because it requires high energy to overcome electrostatic repulsion:- the repulsive force between 2 positive nuclei

89

What is Einstein's equation

E = mc2
=> energy = mass x (speed of light) 2

90

Mass defect

In a fusion reaction particles join together and lose mass. This loss in mass is called the mass defect

91

Mass defect equation

Mass defect = 🔼m
So the energy released = 🔼mc2

92

Properties of a massive star

• will had a greater gravity so theparticles will fuse with more energy which means that more energy is released

93

Main sequence

The stage in a Stars life where the fusion of hydrogen into helium takes place in the core

94

How is energy radiated into the Photosphere

1. the photons of energy from the nuclear fusion taking place in the core of the star travel to the surface by radiation and convection
2. this energy is then radiated from the surface of the sun (photosphere) into space

95

How does a star keep it's equilibrium

Gravity and gas pressure are the 2 forces which act on a star and keep it in equilibrium. Gravity is the inward force and has pressure is the outward force

96

Hertsprung- Russell diagram

1. Stars in the main sequence form a diagonal line
2. For small/medium stars - run out of fuel (hydrogen) so the inward force (gravity) causes the star to collapse brief final episode of fusion and the star expands to form a red giant
3. Eventually cool and contract to a white dwarf
4. For large/huge stars - runs out of fuel and collapses, huge expansion (SUPERGIANT) collapses and explodes (NOVA OR SUPERNOVA) cools and contracts (NEUTRON STAR/ BLACK HOLE)

97

Hubble's law

Plot of the distances of stars from Earth and the speed which they are moving away from us

98

What does Hubble's law suggest

That the universe is expanding (evidence for the Big Bang)

99

Equation from Hubble's law graph

Vr inversely proportional to distance
OR
Vr = constant x distance
=> Vr = H0 x distance
Where H0 = Hubble constant

100

Equation for the age of the universe

Age of the universe = 1/H0

101

Which colour represents the most and least energy in the Hertsprung- Russell diagram

1. Blue indicates the most energy. 2. Red indicates the the least energy

102

Which stars carry out the most hydrogen fusion

Stars in the MAIN SEQUENCE carry out hydrogen fusion

103

Why aren't BLACK HOLES on the Hertsprung-Russell diagram

BLACK HOLES are not on the Hertsprung Russell diagram because they have not luminosity

104

Why is their a relationship between distances to far galaxies and their speeds of recession

The universe started with the Big Bang so is always expanding

105

Why are scientists confident that the relationship between speed of recession and distance of far galaxies is correct

The data is the other theories and we are getting more data which proves the theory and the theory has not yet been disproven

106

What is speed of recess also known as

Velocity

107

Cepheid variable stars

A type of star with luminosity that varies in a regular way; the period of the variation depends on the size of the star

108

How do we work out distance using variable stars

By comparing its real brightness with its apparent brightness