View source for Waves & Particles

=PH2.1 WAVES=

Content
*Progressive waves
*Transverse and longitudinal waves
*Polarisation
*Frequency, wavelength and velocity of waves
*Diffraction
*Interference
*Two-source interference patterns
*Stationary waves

AMPLIFICATION OF CONTENT
Candidates should be able to:

[[2.1 (a)]] understand that a progressive wave transfers energy or information
from a source to a detector without any transfer of matter;

[[2.1 (b)]] distinguish between transverse and longitudinal waves,

[[2.1 (c)]] describe experiments which demonstrate the polarisation of light and
microwaves;

[[2.1 (d)]] explain the terms displacement, amplitude, wavelength, frequency,
period and velocity of a wave,

[[2.1 (e)]] draw and interpret graphs of displacement against time, and
displacement against position for transverse waves only,

[[2.1 (f)]] recall and use the equation c = fλ,

[[2.1 (g)]] be familiar with experiments which demonstrate the diffraction of
water waves, sound waves and microwaves, and understand that
significant diffraction only occurs when λ is of the order of the
dimensions of the obstacle or slit,

[[2.1 (h)]] state, explain and use the principle of superposition,

[[2.1 (i)]] describe an experimental demonstration of two-source interference
for light, appreciating the historical importance of Young's
experiment, and be familiar with experiments which demonstrate two
source interference for water waves, sound waves and microwaves;

[[2.1 (j)]] use the equation λ=ay/D for double-slit interference,

[[2.1 (k)]] show an understanding of path difference, phase difference, and
coherence,

[[2.1 (l)]] state the conditions necessary for two-source interference to be
observed, i.e. constant phase difference, vibrations in the same line,

[[2.1 (m)]] recall the shape of the intensity pattern from a single slit and its effect on double-slit and diffraction grating patterns,

[[2.1 (n)]] use the equation d sin θ = nλ for a diffraction grating,

[[2.1 (o)]] give examples of coherent and incoherent sources,

[[2.1 (p)]] describe experiments which demonstrate polarisation of light,

[[2.1 (q)]] be familiar with experiments which demonstrate stationary waves,
e.g. vibrations of a stretched string and for sound in air,

[[2.1 (r)]] state the differences between stationary and progressive waves,

[[2.1 (s)]] understand that a stationary wave can be regarded as a superposition
of two progressive waves of equal amplitude and frequency,
travelling in opposite directions and that the internodal distance is λ/2

=PH2.2 REFRACTION OF LIGHT=
Content
*Refraction.
*Wave Model of Refraction
*Optical Fibre CommunicationKINEMATICS=

AMPLIFICATION OF CONTENT
Candidates should be able to:

[[2.2 (a)]] recall and use Snell's Law of refraction;

[[2.2 (b)]] recall and use the equations <math>n v=n v</math>n1v1=n2v2 and n1sinθ1=n2sinθ2;

[[2.2 (c)]] understand how Snell's Law relates to the wave model of light
propagation;

[[2.2 (d)]] understand the conditions for total internal reflection and derive and
use the equation for the critical angle
1 n1 sinc=n2;

[[2.2 (e)]] apply the concept of total internal reflection to multimode optical
fibres;

[[2.2 (f)]] appreciate the problem of multi-mode dispersion with optical fibres
in terms of limiting the rate of data transfer and transmission
distance;

[[2.2 (g)]] explain how the introduction of monomode optical fibres has allowed
for much greater transmission rates and distances;

[[2.2 (h)]] compare optical fibre communications to terrestrial microwave links,
satellite links and copper cables for long distance communication.

=PH2.3 PHOTONS=
Content
*The photoelectric effect.
*Photons
*The electromagnetic spectrum
*Line emission and line absorption spectra
*X-rays
*Spontaneous and stimulated emission
*Lasers – energy levels and structure
*The semiconductor laser and its uses
AMPLIFICATION OF CONTENT
Candidates should be able to:

[[2.3 (a)]] describe how the photo-electric effect can be demonstrated

[[2.3 (b)]] describe how the maximum kinetic energy, KEmax, of emitted
electrons can be measured, using a vacuum photocell;

[[2.3 (c)]] sketch a graph of KEmax against frequency of illuminating radiation;

[[2.3 (d)]] understand and recall how a photon picture of light leads to Einstein's
equation, kmax E =hf−φ and how this equation correlates with the
graph of Ekmax against frequency;

[[2.3 (e)]] describe in outline how X-rays are produced in an X-ray tube, and
sketch a graph of intensity against wavelength;

[[2.3 (f)]] recall the characteristic properties and orders of magnitude of the
wavelengths of the radiations in the electromagnetic spectrum;

[[2.3 (g)]] calculate typical photon energies for these radiations;

[[2.3 (h)]] understand in outline how to produce line emission and line
absorption spectra from atoms;

[[2.3 (i)]] describe the appearance of such spectra as seen in a diffraction
grating;

[[2.3 (j)]] understand and use atomic energy level diagrams, together with the
photon hypothesis, to explain line emission and line absorption
spectra;

[[2.3 (k)]] calculate ionisation energies from an energy level diagram;

[[2.3 (l)]] understand and explain the process of stimulated emission and how
this process leads to light emission that is coherent;

[[2.3 (m)]] understand the concept of population inversion (Note: for A level
students the condition N2 > N1 will suffice) and explain that
population inversion is necessary for a laser to operate;

[[2.3 (n)]] understand that population inversion is not (usually) possible with a
2-level energy system;

[[2.3 (o)]] understand how population inversion is attained in 3 and 4-level
energy systems;

[[2.3 (p)]] understand the process of pumping and its purpose;

[[2.3 (q)]] recall the structure of a typical laser i.e. an amplifying medium
between two mirrors, one of which partially transmits light;

[[2.3 (r)]] know the basic structure of a semiconductor diode laser;

[[2.3 (s)]] know that laser systems are far less than 1% efficient in general
(usually around 0.01% efficient) due to pumping losses but that
semiconductor lasers can obtain 70% efficiency and that pumping
requires the application of a p.d. of around 3V;

[[2.3 (t)]] know the advantages and uses of a semiconductor laser i.e. small,
cheap, efficient and used for CDs, DVDs, telecommunication etc.

=PH2.4 MATTER, FORCES AND THE UNIVERSE=
Content
*The nuclear atom
*Leptons and Quarks
*Particle interactions
*Conservation Laws 
AMPLIFICATION OF CONTENT
Candidates should be able to:

[[2.4 (a)]] electrons orbiting in discrete orbits, explaining the composition of the
nucleus in terms of protons and neutrons and expressing the nuclear
and atomic ic structures using the AX
Z notation

[[2.4 (b)]] recall that matter is composed of quarks and leptons – the following
information will be available to candidates in examinations:
Leptons Quarks
particle
(symbol) electron (e−) electron neutrino
(νe) up
(u)
down
(d)
charge (e) − 1 0 23+ 1
3 −
[N.B. No questions will be set involving generations higher than
generation 1.]

[[2.4 (c)]] recall that antiparticles exist to the particles given in the table above,
that the properties of an antiparticle are identical to that of its
corresponding particle apart from having opposite charge, and that
particles and antiparticles annihilate; use the above table to give the
symbols of the antiparticles;

[[2.4 (d)]] recall the following information about the four forces or interactions,
which are experienced by particles:
Interaction Experienced
by Range Comments
Gravitational all particles infinite
very weak – negligible
except in the context of
large objects such as
planets and stars
Weak all particles very short
range
only significant in cases
where the electromagnetic
and strong interactions do
not operate
Electromagnetic all charged
particles infinite
also experienced by neutral
hadrons because they are
composed of quarks
Strong quarks short range
experienced by quarks and
particles composed of
quarks

=PH1.5 RESISTANCE=
CONTENT
*Relationship between current and potential difference.
*Resistance
*Resistivity.
*Variation of resistance with temperature for metals.
*Superconductivity
*Heating effect of an electric current.
AMPLIFICATION OF CONTENT
Candidates should be able to:

[[1.5 (a)]] define potential difference and recall that its unit is the volt (V)
where V = JC-1.

[[1.5 (b)]] sketch I – V graphs for a semiconductor diode, the filament of a
lamp, and a metal wire at constant temperature;

[[1.5 (c)]] state Ohm's Law;

[[1.5 (d)]] define resistance;


[[1.5 (p)]] recall and use P = IV = I^2R = V^2/R.

=PH1.6 D.C. CIRCUITS=
CONTENT
*Series and parallel circuits.
*Combination of resistors.
*The internal resistance of sources.
*The potential divider.
AMPLIFICATION OF CONTENT
Candidates should be able to:

[[1.6 (a)]] understand and recall that the current from a source is equal to the
sum of the currents in the separate branches of a parallel circuit, and
that this is a consequence of conservation of charge;

[[1.6 (b)]] understand and recall that the p.d.s across components in a series
circuit is equal to the p.d. across the supply, and that this is a
consequence of conservation of energy;