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Higher Physics > Particles and waves > Flashcards

Particles and waves Flashcards

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1
Q

A charged particle in an electric field experiences what?

A

A force

(and therefore because f=ma it will accelerate)

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2
Q

Which direction do field lines run for a charged particle or for charged plates?

A

Arrow goes from +ve charge to -ve charge

(or outwards from a +ve point charge, inwards to a -ve point charge)

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3
Q

For a +ve charge in a magnetic field how do you work out which direction it will move?

A

Use left hand rule

  • thuMb is direction it will Move
  • First finger is direction of magnetic Field
  • seCond finger is direction positive Charge is originally going

for negative charges swap to right hand

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4
Q

What is meant by a fundamental particle?

A

A particle that cannot be subdivided into other particles

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5
Q

How many fundamental particles of matter are there?

A

12
6 leptons
6 quarks

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6
Q

In the standard model what type of particle is an electron?

A

A lepton

(and also a fermion)

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7
Q

In the standard model what sort of particle is a proton?

A

A baryon - it is made of 3 quarks

(and it is also a hadron and a fermion)

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8
Q

In the standard model what sort of particle is a neutron?

A

A baryon - it is made of 3 quarks

(and it is also a hadron and a fermion)

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9
Q

What is the force mediating particle for gravity?

A

A graviton

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10
Q

What is the force mediating particle for the electromagnetic force?

A

A photon

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11
Q

What is the force mediating particle for the strong nuclear force?

A

A gluon

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12
Q

What is the force mediating particle for the weak nuclear force?

A

W and Z bosons

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13
Q

What’s the difference between the strong nuclear force and the weak nuclear force

A

Strong nuclear force binds protons and neutrons in the nucleus (and binds quarks in hadrons)

Weak nuclear force is responsible for radioactive decay

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14
Q

What is the general term for a particle made up of quarks?

A

A hadron

there are 2 types of hadron - a baryon and a meson

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15
Q

High-energy collisions between electrons and nucleons, carried out in particle accelerators give the evidence that what exists?

A

quarks

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16
Q

What is an antiparticle?

And what symbol represents it?

A

Every particle has an antiparticle that has SAME mass and OPPOSITE charge

A line over the top of the symbol name means antiparticle

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17
Q

How do we know antimatter exists?

A

Because if particles are annihilated in a particle accelerator then energy is given off

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18
Q

What gave the first evidence of the neutrino?

A

Beta decay

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19
Q

What happens in beta decay?

A
  • a proton in an atom changes to a neutron
  • an electron is emitted
  • a neutrino is emitted
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20
Q

What is the name of a particle made up of a quark-antiquark pair?

A

A meson

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21
Q

What’s the name of a particle made up of 3 quarks

A

a baryon

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22
Q

If two small nuclei combine to make a larger nucleus what type of nuclear reaction is this?

A

Fusion

2 Unite so fUsion

23
Q

If one large nucleus splits to make two smaller nuclei what type of nuclear reaction is this?

A

Fission

2 splIt so fIssion

24
Q

What type of nuclear reaction takes place in the a nuclear power station?

A

fission

25
Q

Why do nuclear fusion reactors need magnetic fields

A

Because you need a high temperature (plasma)

Containers would melt in such high temperatures

26
Q

What is the definition of irradiance

A

The power per unit area incident on a surface.

use the formula sheet I=P/A to help you remember this!

27
Q

When can you use this equation to calculate the irradiance?

I=k/(r squared)

A

If you have a point source

a point source sends light in every direction from a point

remember a laser is NOT a point source

28
Q

What is the name of the effect which is evidence for the particle nature of light.

A

the photoelectric effect

29
Q

What is the name of the effect which is evidence for the wave nature of light.

A

interference

30
Q

Explain what is meant by a coherent wave?

A

A coherent wave has a constant phase relationship (and has the same frequency, wavelength and velocity

31
Q

State 3 facts about the Bohr model of the atom

A

Any 3 of these
* an atom has a small, positively charged central nucleus
* electrons orbit at specific fixed distances from the nucleus and electrons are not allowed to orbit in the space between these specific fixed orbits.
* each of these electron orbits has an energy level associated with it.

32
Q

How is a line in an emission line spectrum produced?

A

When an electron in a higher energy state relaxes to a lower energy state and gives off a photon.

The energy of the photon gives the frequency of the line from E=hf

33
Q

How is a line in an absorption line spectrum produced?

A

If a photon has a frequencies/wavelength giving an energy (E=hf) that is the same as the energy gap between electron energy bands

It is absorbed into the atom and transfers its energy to the electron which moves to a higher energy state

34
Q

In the bohr model - if you had these energy levels how many lines would be produced?

E3_____

E2_____

E1_____

E0_____

A

**6 lines
**
allowed transitions are
E3 to E0
E2 to E0
E1 to E0

E3 to E1
E2 to E1

E3 to E2

35
Q

What is the name of the lowest energy level in the Bohr model of the atom?

A

Ground state

Given symbol E0

36
Q

In the Bohr model, if an electron gains energy it can move to a higher energy level.

We call this state what?

A

Excited state

37
Q

In the Bohr model of an atom, if the electron gains enough energy to completely remove it from the atom it is said to be in what state?

A

Ionisation state

38
Q

Why do we have different colours in a line spectrum?

A

Because different electron transitions release photons with different energy,

These different energies mean different frequencies (and wavelength) because E=hf.

The wavelength/frequency determines the colour.

The data sheet has the wavelengths for the line spectrum of hydrogen

39
Q

How do I find the charge of a proton?

A

The charge on a proton is the same magnitude as the charge of an electron

It’s on the data sheet as the charge of an electron

electron charge is -ve,
proton charge is +ve

40
Q

What is the definition of the critical angle?

A

The angle of incidence such that the angle of refraction is 90 degrees

41
Q

In the equation

n= sin (θ 1) / sin (θ 2)

how do you know which to use for θ 1 and θ 2?

A

θ 1 is always the angle in air

it doesn’t matter if it’s the angle of incidence or the angle of refraction

42
Q

In the photo electric effect - what happens?

A

When you shine light on a material, if a photon of light has enough energy (more than the work function) it knocks an electron out of it’s orbit and it becomes a free electron (called a photo-electron)

photo - photon, electric - electron

43
Q

What’s the symbol for the work function?

A

there is no symbol!

Work function =hf0

this is in the equation Ek=hf-hf0

44
Q

What is the symbol for threshold frequency?

A

f0

45
Q

For the photoelectric effect, if you have a graph of
kinetic energy of electrons against
frequency of the light
how can you work out the threshold frequency?

A

It’s the point where the straight line crosses the x axis

46
Q

When does the photo electric effect take place?

A

If the energy of the light incident on the material is greater than the work function

E > hf0

Or when the frequency of the light is greater than the threshold frequency

f>f0

47
Q

Explain in terms of waves how a minimum in an interference pattern is observed?

A

A crest/peak of a wave meets a trough of a wave

48
Q

Explain in terms of waves how a maximum in an interference pattern is observed?

A

A crest/peak of a wave meets a crest/peak of a wave

49
Q

Explain how the dark lines in the spectrum of sunlight are produced.

A

Photons of certain energies/frequencies are absorbed

In the sun’s atmosphere

50
Q

Explain why a spectrum is produced in a glass prism.

A

Different frequencies/colours have

different refractive indices

so are refracted through different angles

51
Q

Explain why energy is released in a fusion/fission reaction.

A

because mass is converted to energy

E=mc^2. Mass afterwards is less than mass before

52
Q

Explain why the photoelectric effect provides evidence for the particle nature of light?

A

Each photon contains a fixed/discrete
amount of energy

Each photon removes one electron

53
Q

Explain why particles such as leptons and quarks are known as
fundamental particles.

A

Fundamental particles (Leptons and quarks) cannot be subdivided

54
Q

Explain why a fusion reaction is hard to sustain in a nuclear reactor

A

The particles need to be at a very high temperature

Higher Physics (5 decks)

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