Year 1 content Flashcards
What does random errors affect
precision
What does systematic error affects
accuracy
How are random errors mitigated (3)
- reduce % uncertainty
- take repeats
- higher resolution
- more resolution
- use data loggers
How are systematic errors mitigated (2)
- calibrate equipment
- check against known data values
- control environment
define parallax error
when a measurement is taken from the wrong point, due to viewing angle
Difference between repeatability and reproducibility
repeat - tester redoing it
reproduce - 3rd party
resolution for reading
1/2 of smallest division
resolution for measurement
1 smallest division
% uncertainty of set of data
1/2 of range
% uncertainty for gradiant
(best m - worst m)/best m
all SI units (7)
- metre
- kg
- sec
- mole
- amps
- candela
- K
Range of strong force
< 3 fm
repulsive under 0.5 fm
alpha decay eq.
how was anti-electron neutrino discovered
- consitution of energy suggest energy(before) != energy(after)
- suggest anotherb particle have been produced
annhilation and pair production diagram
what does E = mc^2 suggest
energy and mass are interchangable
app. of annihlation (1,4 steps)
PET scanner
1. positron is emitted
2. annihlates electron in body
3. photons are released
4. detected to form 3D image
exchange particle for strong force
gluon
exchange particle for weak force
W boson ( +/-)
exchnage particle for EM
photon
feymann diagram for beta-plus decay
feymann diagram for beta-minus decay
feymann diagram for **electron capture **
feymann diagram for electron-proton collision
Why threshold frq. cannot be explained by wave theory
- wave theory suggest photoelecton can be emitted under any frq.
- contradicts reality
- as only frq > frq 0 emits photo e-
how particle theory backs threshold frq.
- each EM wave travel in packets called photon
- 1 electron absorbs 1 photon
- electron is only emitted when energy is greater than work func.
Define stopping potential
pd needed across metal to stop photoelectron with max KE
5 key points for flourescent lamp
- voltage acc. electron along the tube
- electron collides with Hg atoms - *excitation *
- Hg dexcites - releases UV
- flourescent coating absorbs UV photons - *excitation *
- coating dexcites - emitting visible light photons
experiment that demonstrate particle properties of light
photoelectric effect
de Brogile wavelength - electron diffraction
what happens when speed of electron increases
- wavelength decreases
- diffraction decreases
- closer ring
4 general rules of particles
only stable baryon
proton
4 general rules of particles
how are strange particles created / decayed
- produced in pair by strong
- decay via weak
4 general rules of particles
what does muon decays into
electron (as from heavy electron)
how to build mesons config.
- one particle + one anti-
- by charge
- only kaon have stangeness
formation of stationary waves (5)
- foward wave emitted
- hits boundary - form reflected wave
- both conherent + constant phase difference
- anti-node - constructive interference - in phase
- node - destructive interference - anti-phase
phase diff. - constructive
n λ
phase diff. - destructive
(n+1/2) λ
apperance of white light diffraction
- white central maxima
- showing a range of colour
- with red furthest
- violet closest
condition for TIR
1.going from denser to less dense
2.angle greater than critical angle
what is cladding
surrounding core with optically less dense material
define pulse broadening
causes an overlap of signal, loss of info
define material dispersion
causes ray to travel in different angle and speed
[due to different wavelength]
solution: monochromatic light
define modal dispersion
caused by ray entering at different angle, taking varying paths
solution : reduce diameter of core
define plastic
does not return to orignial shape after deformation
define brittle
little extension before frature under large force
Kirchoff’s 1st law
sum(flow in) = sum(flow out)
at junction
Kirchoff’s 2nd law
emf = sum of voltage consumed
potential divider eq.
key info:
current is same in series ( I1 =I2)
v(R2) = Vout
properties of ideal voltmeter and amnmeter
voltmeter - infinte resistance (short circuit)
amnmeter - no resistance (like wire)
how does resistance change when temp increases:
[metal conductor]
- greater vibration of atoms
- more collision with electrons
- greater resistance
how does resistance change when temp increases:
[ntc thermistor]
- more electrons emitted
- greater no. of charge carriers
- greater current
3 app. of superconductivity
- power cable
- strong magnetic fields - maglev train , medical scanners
Define resonance
amplitude increases significantly when applied force = natural frq.
Difference between free and forced oscillation
Free
* no transfer of energy
* only internal forces
* always at resonance
Forced
* periodic force needed
* to replace energy loss
* WD on resistive forces
Define critical damping
shortest time to return to rest without oscillation
