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;recall and use SI units,

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 1 1 2 2 1 1 2 2 and sin n v=n v n θ=n sinθ ;

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.

PH1.3 ENERGY CONCEPTS

Content

• Work, Power and Energy.

AMPLIFICATION OF CONTENT Candidates should be able to:

1.3 (a) recall the definition of work as the product of a force and distance moved in the direction of the force when the force is constant; calculation of work done, for constant forces, when force is not along the line of motion ( W.D. = Fxcosθ )

1.3 (b) understand that the work done by a varying force is the area under the Force-distance graph,

1.3 (c) recall and use Hooke's law F = kx, and apply this to (b) above to show that elastic potential energy is 1/2 Fx or 1/2 kx^2,

PH1.4 CONDUCTION OF ELECTRICITY

Content

• Electric charge.
• Electric current.
• Nature of charge carriers in conductors.

AMPLIFICATION OF CONTENT Candidates should be able to:

1.4 (a) understand how attraction and repulsion between rubbed insulators can be explained in terms of charges on the surfaces of these insulators, and that just two sorts of charge are involved;

1.4 (b) understand that the name positive charge was arbitrarily given to the sort of charge on an amber rod rubbed with fur, and negative to that on a glass rod rubbed with silk;

1.4 (c) recall that electrons can be shown to have a negative charge, and protons, a positive;

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;