Particles and waves Flashcards by Katie Banister

A charged particle in an electric field experiences what?

A force

(and therefore because f=ma it will accelerate)

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

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

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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What is meant by a fundamental particle?

A particle that cannot be subdivided into other particles

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How many fundamental particles of matter are there?

12
6 leptons
6 quarks

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

A lepton

(and also a fermion)

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

A baryon - it is made of 3 quarks

(and it is also a hadron and a fermion)

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

A baryon - it is made of 3 quarks

(and it is also a hadron and a fermion)

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What is the force mediating particle for gravity?

A graviton

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What is the force mediating particle for the electromagnetic force?

A photon

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

A gluon

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

W and Z bosons

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

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

A hadron

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

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

quarks

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What is an antiparticle?

And what symbol represents it?

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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How do we know antimatter exists?

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

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What gave the first evidence of the neutrino?

Beta decay

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What happens in beta decay?

a proton in an atom changes to a neutron
an electron is emitted
a neutrino is emitted

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

A meson

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

a baryon

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

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Fusion

2 Unite so fUsion

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

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Fission

2 splIt so fIssion

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

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fission

Why do nuclear fusion reactors need magnetic fields

Because you need a high temperature (plasma) Containers would melt in such high temperatures

What is the definition of irradiance

The power per unit area incident on a surface. ## Footnote use the formula sheet I=P/A to help you remember this!

When can you use this equation to calculate the irradiance? I=k/(r squared)

If you have a point source | a point source sends light in **every** direction from a point ## Footnote remember a laser is NOT a point source

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

the photoelectric effect

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

interference

Explain what is meant by a coherent wave?

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

State 3 facts about the Bohr model of the atom

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.

How is a line in an emission line spectrum produced?

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

How is a line in an absorption line spectrum produced?

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

In the bohr model - if you had these energy levels how many lines would be produced? E3_____ E2_____ E1_____ E0_____

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

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

Ground state ## Footnote Given symbol E0

In the Bohr model, if an electron gains energy it can move to a higher energy level. We call this state what?

Excited state

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?

Ionisation state

Why do we have different colours in a line spectrum?

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. ## Footnote The data sheet has the wavelengths for the line spectrum of hydrogen

How do I find the charge of a proton?

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** ## Footnote electron charge is -ve, proton charge is +ve

What is the definition of the critical angle?

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

In the equation n= sin (θ 1) / sin (θ 2) how do you know which to use for θ 1 and θ 2?

θ 1 is always the **angle in air** ## Footnote it doesn't matter if it's the angle of incidence or the angle of refraction

In the photo electric effect - what happens?

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

What's the symbol for the work function?

there is no symbol! Work function =hf0 | this is in the equation Ek=hf-hf0

What is the symbol for threshold frequency?

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?

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

When does the photo electric effect take place?

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

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

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

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

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

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

Photons of certain energies/frequencies are absorbed In the **sun's** atmosphere

Explain why a spectrum is produced in a glass prism.

Different frequencies/colours have different refractive indices so are refracted through different angles

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

because mass is converted to energy ## Footnote E=mc^2. Mass afterwards is less than mass before

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

Each photon contains a fixed/discrete amount of energy Each photon removes one electron

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

Fundamental particles (Leptons and quarks) cannot be subdivided

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

The particles need to be at a very high temperature

Particles and waves Flashcards

(54 cards)