AS Physics
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Chapter 1:
Precision: determined by the range of the measurements
Accuracy: the degree of closeness of the measurements to the true value
Systematic error: consistently more or less than the true value
Random error: scatter about the true value (mean value)
Chapter 2:
Displacement: (min)distance travelled from a point in a specific direction.
Distance: length of actual path travelled
Velocity: rate of change in displacement
Speed: distance/time
Acceleration: rate of change in velocity
Chapter 3:
N1L:
A body continues at constant velocity or rest unless acted on by a resultant
force.
N2L:
resultant force= rate of change of momentum
N3L:
for every action, there is an equal but opposite reaction.
Momentum: mass × velocity
Principle of conservation of momentum:
The total momentum of a system remains constant when there are no resultant
external forces.
Q:Use N2L or N3L to explain change of momentum of A and B is equal and opposite
A:
Force on A by B is equal and opposite with force on B by A
(N3L)
Force is the rate of change of momentum.
(N2L)
Time of collision is the same, hence change of momentum......equal and
opposite....
Q: Judge elastic or inelastic collision
A: M1: Relative speed of approach=? relative speed of separation
M2: Total K.E. of the system before =? Total K.E. after
Chapter 4:
N1L:
A body continues at constant velocity or rest unless acted on by a resultant force.
N2L:
resultant force= rate of change of momentum
N3L:
for every action, there is an equal but opposite reaction.
Upthrust: upward force acting on object when it is immersed in fluid.
Origin of upthrust: pressure difference depends on the depth of difference;
pressure on the bottom surface is greater than that on top;
upward force on the object is greater than downward force.
Force:
Mass:
Weight:
Density:
rate of change of momentum
a measure of body resisting changes in motion
force on object due to gravitational field
mass/volume
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Centre of weight: point at which the whole weight maybe considered to act
Conditions for equilibrium:
resultant force is zero, and resultant moment is zero.
Torque/moment:
product of force and perpendicular distance from a pivot
Couple:
a pair of forces, which are equal in magnitude but opposite in directions
Torque of couple:
one force × perpendicular distance between the two forces
Principle of moments: when the object is in equilibrium, the sum of clockwise
moments about a pivot is equal to the sum of anticlockwise moments
Chapter 5:
Work done： Product of force and distance moved in the direction of the force.
Kinetic energy:
energy of object due to its motion
Gravitational energy: stored energy in object due to height in gravitational field
Elastic energy:
stored energy in object due to deformation
Power: work done/ time taken
Principle of conservation of energy: the total energy in an isolated system is constant
Efficiency:
useful output energy (power)/total input energy (power)
Chapter 6:
Hooke’s law: force is proportional to extension within limit of proportionality.
Elastic potential energy:stored energy in object due to its deformation/extension or
compression
Strain energy: ability to do work as a result of a change of shape of object
Stress: force/cross-sectional area
Strain: extension/original length
Young modulus: stress/strain
Elastic deformation:Remove the load and the spring returns to its original length
Plastic deformation:Remove the load and the spring can not return to its original length
Elastic limit: point beyond which the spring does not return to its original length when the
load is removed /the force beyond which the spring becomes permanently
deformed
Chapter 7:
Transverse wave: vibration of particles perpendicular to direction of energy transfer
Longitudinal wave: vibration of particles parallel to /along the direction of energy transfer
Progressive wave: transfer of energy as a result of oscillations/vibrations
Displacement of wave: distance of a point on wave from rest position
Amplitude: maximum displacement from rest position
Wavelength: distance between adjacent wavefronts
Frequency: number of oscillations per unit time of a point on the wave
Period: time taken for one complete oscillation
Rarefaction: region of low pressure in longitudinal wave
Compression: region of high pressure in longitudinal wave
Wavefront: a surface in which all the particles on it vibrate in phase
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Diffraction: when a wave is incident on an edge(obstacle), wave spreads out
Phase difference: a fraction of cycle between two oscillating particles
Wave speed: speed at which energy is transferred/ speed of wavefront
Polarised wave: vibrations are in one direction and normal to direction of wave energy
transfer
Doppler effect: difference in the observed/apparent frequency when the source is moving
relative to the observer.
Chapter 8:
①Stationary wave:
Principle of superposition:
When two (or more) waves meet (B1), resultant displacement
(B1)is the sum of individual displacements (B1).
Interference: same as principle of superposition
Difference between stationary wave and progressive:
Stationary wave: no energy transfer/ nodes or antinodes/ adjacent particles in one loop
are in phase/ amplitude varies from 0 at the nodes to maximum at the antinodes
Progressive wave : transfer energy/ no nodes or antinodes/ adjcanent particles in a loop are
out of phase/all particles have same amplitude
Conditions for forming stationary wave:
1. Two waves in opposite directions meet; (B1)
2. Waves are same type, same frequency (wavelength,speed), same amplitude (B1)
e.g. (incident wave and its reflected wave)
How to form stationary wave:
1. Incident wave reflected at fixed end; (B1)
2. Incident wave and reflected wave superpose/interfere. (B1)
3. They are same frequency, same type, same wavelength......(B1)
Node: (points where is) zero amplitude/displacement
Anti-node: (points where is) maximum amplitude
②Interference:
Coherence: constant phase difference
How to produce two sources of coherent waves and observe interfering waves
※Two dippers are connected to the same vibrating source, (B1) lamp with viewing
screen in opposite side of tank (B1) and use strobe to freeze the picture (B1)
※Two loudspeaker are connected to the same vibrating source;
※Microwaves transmitter transmits towards a double gap in metal barrier;
※A laser(monochromatic) light is incident on double slits on a thin plate;
Constructive interference: path difference is a whole number of wavelength, n
or phase difference is 0
Destructive interference: path difference is an odd number of half wavelength, n  12 
or phase difference is 180°.
Conditions for the two waves may interfere (maxima/minima):
1. Same type (both transverse or longitudinal) waves meet a point (B1)
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2 Coherent (constant phase difference) (B1)
3. Same direction of plorisation, (B1)
4. Path difference is 0 ,  , 2 ,.... / path difference is
How interference maximum/ (minimum) is formed?
 3
,
,....
2 2
The path difference between two coherent waves is n ,/ ( n  12  )or phase
difference is 0,/ ( 180  n  360 )


如果解释为什么在某点是 maximum/bright fringe?
三步！ IMPORTANT!!
1. Waves meet/overlap at the point
2. Path difference is ____, and phase difference is ______.
3.
B1
B1
So it’s _______/_________interference， intensity is maximum/minimum
B1
注意：四种波干涉中，除了可见光描述可以用 fringe..., 其他只能用 maximum/minimum.
可见光干涉用 fringe, 光栅用 line
③Diffraction grating:
Diffraction: When a wave passes through an edge (obstacle), wave spreads (out).
Chapter 9-10:
Define e.m.f of a source
Energy transferred (from chemical energy to electrical energy) in driving unit charge
around the complete circuit
Define electrical potential difference
energy transferred (electrical energy to other forms)per unit charge
Disgusting e.m.f. of a source and p.d. across a resistor
Both measure energy (work)/charge
For e.m.f. transfer chemical energy to electrical energy
For p.d. transfer electrical energy to thermal energy/other forms
Define resistance of a resistor
Potential difference/current
Define internal resistance
Resistance of the cell causing loss of voltage ( energy loss in cell)
Current
Charge flowing through per unit time/ rate of charge flow/ flow of charge carrier
Define the ohm
Volt/ampere
Define the volt
Joule/coulomb
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Kirchhoff’s first law:
Sum of currents into junction=sum of currents out of junction
Or sum of currents at a junction is zero. -------linking with conservation of charge
Kirchhoff’s second law:
Sum of e.m.f. (s) =sum of p.d. (s) around a loop. --------- linking with conservation of
energy
Why terminal potential difference is less than e.m.f. of the battery?
---Thermal energy is dissipated in internal resistance.
Why the terminal potential difference is not constant?
There is potential difference between internal resistance
(B1)
(Resistance changes as temperature changes, so current changes) As the current changes,
the p.d. across internal resistance changes
(B1)
V=E-Ir, so terminal potential difference, V is not constant
(B1)
Chapter 11:
①
Alpha-particle: helium nucleus or 2 protons and 2 neutrons
Nuclear structure of atom
Most alpha-particles pass straight without deflection or a little deflection
-------------------Most of an atom is empty space
Minority/ a few alpha particles deflect with a large angle (angle >10)
------------------ Nucleus is positively-charged with large mass (small volume)
Extremely small amount of alpha-particles deflected back (angle > 90)
------------------- the nucleus is charged
B1
Most mass of the atom is in the nucleus
B1
②
"   " decay: electron+antineutrino / "   " decay: positron +neutrino
Q: Why the 

particles are emitted with a range of kinetic energies?
A: Antineutrino is emitted and energy can be shared with antineutrino.
Mass deflect
Q:
A:
mass changes to “seen” as form of energy.
 -decay energy releasing ( E  mc 2 )
K.E. of nucleus
K.E. of  nucleus
  radiation
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AS Physics
Q:
LLuu
 -decay energy releasing ( E  mc 2 )
A:
K.E. of nucleus
K.E. of  particles
Neutrino or antineutrino is produced
  radiation
Quantities conserved in decay:
Proton number
Nucleon number
Momentum
Mass-energy
③
Four fundamental force/interaction:
Gravitational force
Electromagnetic force
Strong nuclear force
通过引力子？交换作用
通过光子交换作用
( 0.5  l  4 fm attraction)
Weak nuclear force (  decay )
Fundamental particles: lepton,
Hadron
Particles
通过胶子/介子交换作用
0
通过玻色子 （ W , Z ）交换作用

quark......gauge bosons
（规范玻色子不考）
Proton:
uud
Baryon: made up of three quarks
.......
Neutron: udd
Meson: made up of two quarks (a quark + an other anti-quark)
强子基本都是由夸克和反夸克组成的！
Lepton
Electron, positron............
Neutrino, antineutrino.............
e 
 
 ve 
 
 
v 
 
 
  .......
 v 
Hadron: 参与强相互作用，也可参与弱相互作用,带电的还可参与电磁相互作用
Lepton: 不参与强相互作用，参与弱相互作用,带电的还可参与电磁相互作用
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AS Physics
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Up
Down
Strange
Charm
Bottom
top
2
 e
3
1
 e
3
1
 e
3
2
 e
3
1
 e
3
2
 e
3
Q： Determine, in terms of the elementary charge, e, the charge of proton.
A: proton is consist of two up quark and one down quark
(uud)
B1
Up quark is +2/3 e and down quark is -1/3 e
B1
Charge= 2 ×+2/3 e- 1/3 e
= +e
B1
Q: during 

decay, describe the change to the quark composition
A: up down down changes to up up down
B1
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