#### The eye and colour vision

The physics of the eye, its performance and colour vision: refraction and accommodation; photoreceptors and resolution; compromises in visual performance.

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On scales much bigger than the wavelength, rays explain the behaviour of interfaces, mirrors, lenses, optical instruments, including telescopes and microscopes.

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White light comprises colours in the visible spectrum. The electromagnetic spectrum. Speed of light. Young's experiment and waves. Quanta and photons.

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Sound is produced in the larynx; filtering it in the vocal tract produces formants and phonemes. The acoustics, mechanics and some neurobiology of hearing. Pitch perception.

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Reflecting waves gives standing waves, which can be resonances. Standing waves on strings and in pipes and plates.

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Superposing waves with different frequencies gives beats and Tartini tones. Removing beats gives consonance. Tuning consonances gives temperament.

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Frequency, amplitude, envelope and spectrum affect pitch, loudness and timbre. All are discussed and quantified here.

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Moving either source or receiver produces a frequency shift called the Doppler effect, which we measure and analyse.

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Sound is a longitudinal wave of variations in pressure and density. We derive and measure its speed.

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The wave equation and its physical origin. Power in a wave and its relation to intensity in radiation.

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In an extended medium, inertia and a restoring force can lead to waves, which reflect at boundaries, either erect or inverted.

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Inertia and restoring forces can, with low friction or damping, lead to oscillations and resonance. We analyse the mechanics of vibrations.

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The inverse square law explains planetary motion - and apples falling. Newton's law, measuring G, calculating orbits.

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Torques produce angular acceleration, moment of inertia 'resists' it. Rotational kinetic energy and angular momentum.

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p=mv. If external forces are zero, momentum is conserved. In collisions, energy may be conserved (elastic) or not (inelastic).

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In finite objects, the total external force equals the total mass times the acceleration of a point called the centre of mass.

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The total work done on an object equals the increase in its kinetic energy. For conservative forces, we can define potential energy.

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Carefully distinguish mass and weight. Hooke's law quantifies deformation. Contact forces have normal and frictional components.

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F=ma (laws 1&2). Forces come in pairs that add to zero (3). Newton's laws apply in inertial frames of reference. Some common approximations made in applying them.

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In simple harmonic motion, displacement, velocity and acceleration vary sinusoidally with time, but with different phases.

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Uniform circular motion: angular displacement and velocity are introduced and centripetal acceleration is determined.

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Motion with uniform acceleration, such as in a uniform gravitational (or electric) field is projectile motion, analysed here with examples.

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Kinematics quantifies motion without explaining the causes of it. Here we study accelerations that are zero, positive or negative.

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How extending Galileo's relativity to magnetism leads to Einstein's relativity, time dilation, length contraction, relativity of simultaneity and E=mc2 .

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