P3 Topic 5- Particles In Action

For edexcel 360science triple science, it is extension for physics

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Kinetic theory

Kinetic theory tells us that gases consist of very small particles, they are moving in random directions, collide with each other and with the walls and bounce off.

Absolute zero- When you increase the temperature of something, the particles gain energy so they move more quickly or vibrate.

Also when you decrease you reduce the energy

The coldest anything can get is -273C or 0K which is zero Kelvin

Celsius to Kelvin you add 273

Kelvin to Celsius you subtract 273

If you increase the temperature of a gas it gains more energy

The temperature of a gas (K) is proportional to the average kinetic energy of its particles

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Kinetic theory and pressure in gases

When gases collide they exert a force on the thing, in a sealed container gas particles smash against the walls creating an outward pressure.

Pressure Depends on:

How fast particles are going

How often they hit the walls

Temperature and pressure are proportional, double the temp so you get double the pressure

Bigger container= less pressure because of fewer collisions

Pressure/Temperature (K)=Constant - for sealed containers

Pressure x Volume/ Temperature (K)= Constant P1 x V1/ T1= P2 X V2/ T2

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Paticles in Atoms

Positron are opposite of electrons, have the same mass but opposite charges, they get annihilated when electron meets it.

Neutron- More penetrating then alpha and beta

not ionising but gets absorbed by the nuclei of an atom which makes a nucleus radioactive.They get absorbed by light nuclei best such as hydrogen so things such as water, polythene or concrete used to make neutron shielding. Also thick lead is used because gamma rays are emitted

They emit ionising radiation such as gamma, beta and alpha

Alpha Beta Gamma What is it Helium Nucleus Electron EM wave speed and weight Slow & Heavy Light & Fast No mass & Very fast Ionising Strongly Moderately Weakly Stopped by Paper, skin etc Thin metal Lead and thin concrete

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Paticles in Atoms

Neutrons difficult to detect because of being neutral, so they are detected by nuclear decays from nuclei.

A isotope above the curve has too many neutrons to be stable

A isotope below the curve has too few neutrons to be stable

B- happens when there are too many neutrons then protons so a neutron is changed into a proton. Emits electron

B+ happens when there are less neutrons, so a proton gets changed into a neutron. Emits positron

Alpha happens in heavy nuclei such as uranium, radium etc so the nuclei are too massive to be stable. The proton number then decreases by 2 and nucleon by 4.

Gamma happens when Nuclei has too much energy, it happens after alpha or beta decay because the nucleus has excess energy so it loses energy by emitting gamma rays.

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Fundamental and other particles

Electrons and Positrons are fundamental particles because you cant split them up into something smaller

You can make new fundamental particles by making 2 protons collide at a high speed, so the energy turns into mass and this makes matter and anti matter. So antimatter has antiparticles which can be fundamental particles.

Protons and neutrons are NOT fundamental particles because quarks make them.

Proton- 2ups and 1 down

Neutron- 2 downs 1 up Quarks- Up= 2/3 Down= -1/3

When Quarks change they turn into Electrons or Positron:

When neutron turns into proton electrons are produced to make it balanced so B- decay

When protons turn into neutron a positron is produced making it balanced so B+ decay

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Electron beams

Electron guns (Cathode ray tubes) use Thermionic emission

The heater heats the cathode which gives energy to the electrons, then the electrons boil off (escape) this is called Thermionic emission

The electrons then accelerate as they're pulled towards the anode, it has a gap which channels the electrons into an electron beam

The electric field between the charged metal deflects the electron beam

The phosphorescent screen glows when electrons hit it

Kinetic energy of an electron (J)= Charge of electron (C) x Accelerating voltage (V)

Current(I)= Charge (n x e)/ time(t) n= charge on electron e= number of electrons

Electron charge= -1.6 x 10^-19 C C= Coulombs

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Electron beam

Electron beam is deflected by an electric field:

It is attracted by a positive charge and repelled by a negative charge.

2 Pairs of charge metal plated are used to deflect the electron, one deflects it up and down which is the Y plates and the X plates move it left or right

Particles are deflected more by:

  • Bigger charge on plates
  • Bugger charge on particles
  • Slower moving particles
  • Lighter particles

Particles are less deflected by:

  • Smaller charge on plates
  • Smaller charge on particles
  • Faster moving particles
  • Heavier particles
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Electron beam

Electron guns are used in TVs, Oscilloscopes and X-rays

Oscilloscope is something which displays the voltage and frequency of an electrical signal. Y axis = Voltage and X axis= Time

TV tubes, PC monitors and oscilloscope have an electron hitting a screen covered in phosphorescent chemicals, which these chemicals emit light

Electron beams produce X-rays by by having no deflecting plates or phosphorescent screen. They have a positively charged target, when electrons hit the target the Kinetic energy is converted to X-rays.

Particles Accelerators such as CERN, they smash up particles in extremely fast speed to see what happens, what is made from them etc. It gives clues how the universe was made and if theorys such as Hugson boson theory is correct. It cost billions of pounds so research is done internationally.

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Former Member


hey...This is reeely guurrd thanks soooo muchhhh...



skeen sabrin



Thnx..This Is Very Helpfull..:)



Thank u...i haaaaaate physics =]



u got topic 6..by any chance?



can u put up topic 6





Miss KHP


GREAT revision source! Well laid out, colourful and summarised. Good method to learn about the particles in action. 

Good for Edexcel P3



this is fab, thnx ;)



on slide 7 is it supposed to be bugger or bigger charge on the particles?

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