P&W Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

What is an order of magnitude?

A

It is a power of 10

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

State what is meant by the term “fermion”

A

A fermion is a matter particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

State what is meant by the term “boson”

A

A boson is a force mediating particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Quarks are ______

A

fermions (i.e. matter particles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Leptons are ________

A

fermions (i.e. matter particles)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

List the 6 quarks

A

Up down strange charm top bottom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

List the 6 leptons

A

electron, muon, tau, electron neutrino, muon neutrino, tau neutrino

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

List the 4 force mediating particles and their associated force

A

Photon (electromagnetic force), Z & W+- bosons (weak force), gluon (strong force)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which force is missing from the Standard Model

A

Gravity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the standard model?

A

A model of fundamental particles and their interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are hadrons made up of?

A

Hadrons are composite particles made of quarks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Baryons are a type of ________ and they are therefore made-up of ________

A

hadron, quarks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Mesons are a type of ________ and they are therefore made-up of ________

A

hadron, quarks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Baryons are made of _______ quarks

A

3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Mesons are made of…

A

a quark-antiquark pair

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe beta decay and how it is evidence for the existence of the neutrino

A

beta decay is when a neutron turns into a proton, electron and an anti electron neutrino. The mass after beta decay was much smaller than could be accounted for by mass-energy conversion and pointed to the existence of a new particle, the neutrino

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

State what is meant by “anti-matter”

A

Every particle in the standard model has a corresponding anti-particle, identical in every way except charge. These particles are called “anti-matter”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

State one piece of evidence for the existence of antimatter.

A

When matter meets antimatter they annihilate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What do electric field lines show?

A

They point from positive to negative and show which way a positive test charge would move if it were to be placed in the field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Describe the process of drawing electric field lines

A

Imagine placing a small positive charge near the distribution of charges in question. Now imagine and draw which way it would move. Repeat this for evenly-spaced locations around the distribution

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What do charged particles experience in an electric field?

A

An unbalanced force. They therefore accelerate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Opposite charges _____; like charges _____

A

Opposite charges attract like charges repel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

State the definition of potential difference

A

Potential difference is a measure of the work done W in moving a charge Q against an electric field i.e. V=W/Q voltage is a measure of the energy per unit charge.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Magnetic field lines point from _____ to ______.

A

Magnetic field lines point from North to South.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe a method to determine the motion of charges particles in a magnetic field

A
  1. Point fingers in direction of field. 2. Point thumb in direction of velocity. 3. The deflection direction is given by the backhand direction for positive charges and the forehand direction for negative charges
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Describe how a particle accelerator words

A

In a particle accelerator an electric field is used to change the particle’s speed (SQA word: accelerate) while it is most common to use a magnetic field to change the particle’s direction (SQA word: deflect). High energy collisions produce new particles.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

State what is meant by “nuclear fission”

A

A big nucleus splits into two smaller nuclei, converting some mass to energy in the process

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Describe how to tell if nuclear fission is spontaneous or induced

A

Induced is usually caused by neutron bombardment. Spontaneous has no trigger

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe induced fission

A

A nucleus is forced to split by neutron bombardment.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How can you tell from a nuclear equation whether it describes spontaneous or induced fission?

A

A neutron will be present in the reactants for induced fission but absent for spontaneous fission.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

How can you tell from a nuclear equation whether it shows fission or fusion?

A

If the equation is for fission, a nuclear species with larger mass number will split into two, each with smaller mass numbers. For fusion two lighter atomic species will join to make one heavier one.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

State what is meant by “nuclear fusion”

A

Two lighter nuclei join to make a bigger nucleus, releasing energy by converting mass to energy in the process

33
Q

How does the mass of the products of a nuclear reaction compare to the mass of reactants?

A

The products are less massive than the reactants. The difference in mass is converted to energy

34
Q

What is required for nuclear fusion reactors and what problem does this create for the design of the reactor?

A

Fusion reactors require charged particles at a very high temperature (i.e. a plasma). The plasma is too hot to be contained by anything other than magnetic fields. A fusion reactor therefore must levitate the plasma in a magnetic field.

35
Q

State one piece of evidence for the particle model of light

A

photoelectric effect

36
Q

State one piece of evidence for the wave model of light

A

interference of light

37
Q

Describe the photoelectric effect

A

Photons of high enough energy can eject electrons from the surface of a material (photoemission).

38
Q

State what is meant by the term “work function”

A

The minimum energy required to cause photoemission (i.e. eject an electron from a metal)

39
Q

State what is meant by “photoemission”

A

Photoemission is the ejection of electrons from a material by light

40
Q

State what is meant by the term “threshold frequency”

A

Minimum frequency of incident photon required to cause photoemission

41
Q

How is threshold frequency related to work function?

A

The threshold frequency is the minimum energy of photon required to cause photoemission. From this the work function may be calculated using E=hf

42
Q

If one photon hits the surface of a material with energy greater than its work function how many electrons will be ejected?

A

1

43
Q

Explain why positively charged metal plates will not show the photoelectric effect.

A

Positively charges plates have already had their electrons removed.

44
Q

A photon with energy greater than the work function strikes a material. Where does the extra energy go?

A

Into the kinetic energy of the ejected electron

45
Q

What is meant by the term “coherence”?

A

Coherence describes waves which have a constant phase relationship

46
Q

When does constructive interference happen?

A

When waves meet exactly in phase i.e. peak to peak and trough to trough

47
Q

When does destructive interference happen?

A

When waves meet exactly out of phase i.e. peak to trough and trough to peak

48
Q

What happens during constructive interference?

A

Waves combine to make a maximum

49
Q

What happens during destructive interference?

A

Waves cancel out to make a maximum

50
Q

What is path difference?

A

The difference in the length of the paths taken by two waves

51
Q

State the condition for constructive interference

A

path difference = mλ

52
Q

State the condition for destructive interference

A

path difference = (m+1/2)λ

53
Q

How do you calculate slit separation given the number of lines per mm on a diffraction grating?

A

Take the reciprocal of the number of lines per mm

54
Q

What does θ represent in the grating equation?

A

The angle between the central maximum and the order under consideration

55
Q

What does m represent in the grating equation?

A

Order number

56
Q

State what is meant by “absolute refractive index”

A

Absolute refractive index of a medium is the ratio of the speed of light in a vacuum to the speed of light in the medium

57
Q

Refractive index is always greater than ____

A

1

58
Q

How does refractive index change with frequency?

A

Refractive index increases as frequency increases i.e. higher frequencies refract more than lower frequencies

59
Q

In the equation for refractive index, θ1 must be greater/less than θ2 to ensure refractive index is greater than 1

A

In the equation for refractive index, θ1 must be greater than θ2 to ensure refractive index is greater than 1

60
Q

When going from air to glass, light bends towards/away from the normal and when going from glass to air it bends towards/away from the normal unless it travels along the ________

A

When going from air to glass, light bends towards from the normal and when going from glass to air it bends away from the normal unless it travels along the normal

61
Q

Describe an experiment to measure the refractive index of a material

A
  1. Send light into the material 2. Measure angle of incidence (θ1) and angle of refraction (θ2) 3. Plot sin(θ2) against sin(θ1) 4. Gradient of line of best fit is refractive index n
62
Q

State what is meant by the term “critical angle”

A

The critical angle θc of a medium is the angle of incidence inside the medium which results in a refracted angle of 90°.

63
Q

State what is meant by “total internal reflection”

A

total internal reflection is the name given to the complete reflection of light when it travels from a more dense towards a less dense medium at an angle greater then the critical angle for the medium it is in. No light is transmitted externally into the less dense medium, hence the name total internal reflection.

64
Q

State what is meant by “irradiance”

A

Irradiance is the power per unit area incident upon a surface

65
Q

What is an inverse square law?

A

An inverse square law means that as one quantity increases the other will decrease as the reciprocal squared.

66
Q

Describe how irradiance varies with distance from a point source?

A

irradiance follows the inverse square law i.e. if the distance is doubled (x2) then the irradiance will quarter

67
Q

Describe the Bohr model of the atom

A

The Bohr model pictures electrons orbiting the nucleus at certain distances, like planets around the sun.

68
Q

Describe how the Bohr model is related to energy levels

A

The Bohr model has electrons only occupying certain distances from the nucleus. The electron will have a different amount of energy at each particular distance. These different energies are called energy levels. Levels which are closer to the nucleus are lower in energy and those further away higher.

69
Q

What is the “ground state”?

A

The lowest energy level which an electron can occupy

70
Q

What is an “excited state”?

A

Any energy level above the ground state. When an electron occupies any level above the ground state is is said to be in an excited state

71
Q

State what is meant by “energy levels”

A

Energy levels are particular values of energy which an electron can have. The electron cannot have any energy, it can only have energy corresponding to an energy level

72
Q

What is chosen to be the zero of potential energy in the Bohr model?

A

When the electron is completely removed (i.e. ionised) from the atom. [Zero potential energy is defined as being at infinite distance from the atom. This means the electron is free from the electrostatic influence of the atom and therefore is given no potential energy by the atom.]

73
Q

What is meant by the term “ionisation” in relation to the Bohr model of the atom?

A

Ionisation is when an electron is completely removed from an atom. This means it occupies no energy level and its potential energy is no longer negative.

74
Q

What happens when an electron falls from a higher energy level to a lower one?

A

Light is emitted with energy equal to the difference in energy between the two levels. The frequency of light emitted can be calculated using E2 - E1 = hf

75
Q

State what is meant by the term “emission line spectrum”

A

An emission line spectrum shows the wavelengths of light emitted due to electron transitions between particular energy levels

76
Q

Describe how line emission spectra are produced

A

Exciteed electrons in an atom drop from higher energy levels to lower ones. As they do this, light is emitted at a frequency correspoinding to the difference in energy of each level. Light is only emitted at particular frequencies; each frequency is shown as a coloured line in an emision spectrum.

77
Q

Describe how continuouus emission spectra are produced

A

Continuous emission spectra are produced when electrons drop between many energy levels with tiny differences between them e.g. in a hot solid such as the sun.

78
Q

Describe how absorbtion spectra are produced

A

Absorption spectra occur when the electrons in an atom absorb specific energies of photons and the electrons move up to the relevant energy levels. An observer will see dark lines in a continuous emission spectrum corresponding to the absorbed wavelengths.

79
Q

State what is meant by the term “Fraunhofer lines”

A

Fraunhofer lines in the continuous emission spectrum of the sun are evidence for the composition of its outer atmosphere.