Exam Flashcards
What is the equation to caluclate the velocity of electrons in a beam as they are accelerated through a pd
V= square rot of 2ev/m
Derive r=p/BQ
- F=mv2/2
- F=BQV
BQV = MV2/r
BQ= MV/r
p=Mv
BQ=p/r
r= p/BQ
Why will a charged particle moving in a bubble/cloud chamber show a decreasing radius
They lose energy through ionisation and therefore their velocities decrease and due to the equation r=(mv) /bq and mBQ are all fixed the radius decreases.
If the magnetic field is out of the page what charge is the particle
Positively charged
If the magnetic field is into the page what charge is the particle
Negatively charged
How do you convert from Mev/c2 to Kg
Mev> Joules > kg
E=mc2
m= E/c2 = J/3x1082 = Kg
Cov=nverting from Kg to Mev/c2
- E=mc2
- Convert the E into Mev
- M= E/c2 so ev= Mev/c2
calculate the energy in Mev and just add c2 for the denominator as Mass= ev/c2
Characteristics of a Linac acceleartaor
- Uses electric field taht is alternaring
- The a.c supply has a constant frequency
- The drift tubes get progressively linger to ensure electrons are inside each tube for a constant amount of time
- In each tube the elctrons travel at a constant velcoity
Characteristics of a Cyclottron
- Uses a magnetic and alternating electric field
- Has D shaped electroded attached to a.c supply
- Placed in a vacuum chabger and the magnetic field acts at right angles
What do antipartiles have
The same mass as the original particle
Opposite charge to the original particle
Opposite spin to the original particle
Baryon number and charge of proton
Baryon number = 1
charge = +1
Baryon number and charge of neutron
Baryon number = 1
charge = 0
Lepton number and charge of electron
Lepton number = 1
charge= -1
Lepton number and charge of muon
Lepton number = 1
charge= -1
Lepton/ baryon number of pion +
Lepton/baryon number= 0
charge= +1
Lepton/ baryon number of pion +
Lepton/baryon number= 0
charge= 0
lepton number of neutrino and charge
Lepton number = 1
charge= 0
The standard model
- Fundamental particles are made out of quarks and leptons
- Baryons are made up of 3 quarks
- Mesons are made of a quark and anti-quark
- There are 6 quarks or 6 leptons
- Each particle has an antiparticle
Explain how a higher p.d is produced across the secondary coil
- The alternating p.d causes an alternating current across the primary coil which causes an alternating magnetic field around the primary coil
- The iron core links the magnetic field to the secondary coil
- The secondary coil experiences a change in magnetic flux linkage. As there is a rate of change of magnetic flux linkage an emf is induced through the secondary coil
- As the secondary coil as more turns ,N than the primary coil the emf induced in the secondary coil is higher
State the equations used to calculate minumum distance between charges
W= delta V q
delta V= KQ/r2
W= KQq/r2-
How to calculate current given frequency
Frequency x charge
Explain why the value of ε varies between a maximum value and zero.
- Induced emf is equal to the rate of change of flux linkage
- Mximum emf is when coil is horizontal as the side of the coil is cutting the flux at maximum rate
- WHn the coil is vertical the side of the coil is not cutting the magnetic field lines
Rutherford experiemt observations and conclusions
- ALpha particles that were fired mostly passed starigh through indicating the atom consists of mostly empty space
- Only a small number of alpha particles were deflected indicating that the nuclues must have a small volume as only few alpha particles got close enough to be deflected
- The alpha particles sometimes deflected at an angle greater than 90 degrees meanng that the nucleus has a high mass as the alpha particle is being deflected and not the nucleus . The charge is also concntrated in the nculeus o that the repulsive force is high
