Waves, Light & Quanta

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Waves, Light & Quanta. Tim Freegarde. Web Gallery of Art; National Gallery, London. Circumference of the earth. (Tropic of Cancer). Eratosthenes of Cyrene (276-195 BC). 5000 stadia ~ 5000 x 180m = 900 km. α = β ~ 1/50 circle. Radius astronomicus. Reinerus Gemma-Frisius , Leuven. - PowerPoint PPT Presentation

Transcript of Waves, Light & Quanta

  • Waves, Light & QuantaTim FreegardeWeb Gallery of Art; National Gallery, London

  • Circumference of the earthEratosthenes of Cyrene (276-195 BC)5000 stadia ~ 5000 x 180m = 900 km = ~ 1/50 circle(Tropic of Cancer)

  • Radius astronomicusReinerus Gemma-Frisius, Leuvenmeasurement of celestial angular distances

  • Camera obscurasolar eclipse, 24 Jan 1544Reinerus Gemma-Frisius, Leuvende radio astronomica et geometrica, 1545

  • Pinhole camerafoilscreenpinholeobjectimage

  • Rayslight travels in straight linesABCSPSPshortest distance between two points

  • The nature of lightlight travels between two points by the shortest distance

  • Rayslight travels in straight linesABCSPSPshortest distance between two points

  • Reflectionlight travels in straight linesSPSPshortest distance between two points

  • Reflection at a curved surfacelight travels in straight linesshortest distance between two pointssuppose we design a surface so that all routes are the same length?

  • Conic sectionsdirectrixfocusPARABOLAfocus Afocus BELLIPSE

  • Concave mirrorlight travels in straight linesshortest distance between two pointsequal times to focusRf

  • Lenses and refractionTommaso da Modena (1325-1379)Chiesa San Nicol, TrevisoIbn al-Haytham Alhazen(965-1039)

  • Fermats principle of least timerefraction at a plane surfacePierre de Fermat (1601-1665)ABCSPSP

  • Fermats principle of least timerefraction at a plane surfaceSPSPlight rays follow the path of least time between two points

  • Snells law of refractionrefraction at a plane surfaceSPSPlight rays follow the path of least time between two points

  • The nature of lightlight travels between two points by the shortest distancelight travels between two points by the quickest route (least time)light travels between two points by the route for which the time taken is a stationary value

    Calculate earth circumferenceInclude error calculationDemonstrate use of sextantChamber, not cameraNot radio astronomyDemonstrate pinhole cameraPinTripodCalculate image size and resolutionCalculate shortest distanceExplain that principle can then be applied to more complex routesCalculate shortest distanceExplain that principle can then be applied to more complex routesCalculate shortest distanceExplain that principle can then be applied to more complex routesFirst curved mirrors of metal (eg bowl, spoon)Construct surfaces of equal time ray paths.Parabola: may be lines of equal distance to focus and directrix outside parabola so equal total distance from directrix to focus via parabola.Lenses polished crystals and water-filled glass flasks known in ancient Egypt (C6BC), Rome (C1AD) and Moorish Spain (Berbers, C9AD)Alhazen (Basra, Egypt) described many aspects of optics, including the principles of the camera obscura, in his Book of Optics (1021), and described experiments with lenses, mirrors, refraction etc.Further advances with development of glassblowing in the C13, Venice.Routine, if notable, use by C14.

    Calculate shortest distanceExplain that principle can then be applied to more complex routes