Tag Archives: Light

Waves,Properties and Their Applications.

4 Sep
  1. Doppler Sim 1.0

    Doppler Sim 1.0 (Photo credit: J.Gabás Esteban)

    316/365 Revision Week: Partial Differential Eq...

    316/365 Revision Week: Partial Differential Equations (Photo credit: stuartpilbrow)

    Electromagnetic Spectrum

    Electromagnetic Spectrum (Photo credit: hummingcrow)

    Change of wavelength caused by motion of the s...

    Change of wavelength caused by motion of the source. (Photo credit: Wikipedia)

    The principle of many refractometers.

    The principle of many refractometers. (Photo credit: Wikipedia)

    longitudinal wave

    longitudinal wave (Photo credit: mhobl)

    English: Propagation of a plane compression wa...

    English: Propagation of a plane compression wave (impulse); made with Scilab and Jasc Animation Shop 2.02 Deutsch: Vorstellung einer Longitudinalwelle (impuls); gemacht mit Scilab und Jasc Animation Shop 2.02 Français : Propagation d’une onde de compression plane (impulsion) ; créé avec Scilab et Jasc Animation Shop 2.02 (Photo credit: Wikipedia)

    Doppler-Effekt Animation

    Doppler-Effekt Animation (Photo credit: Wikipedia)

    Total internal reflection in a bar of PMMA. Th...

    Total internal reflection in a bar of PMMA. The laser is HeNe laser (Photo credit: Wikipedia)

    Illustration of Wave equation

    Illustration of Wave equation (Photo credit: Wikipedia)

    Total internal reflection

    Total internal reflection (Photo credit: Wikipedia)

    English: Compressional wave (longitudinal wave...

    Refractive Indices
    Refractive Indices (Photo credit: the_himay)
    English: Illustration of wavefronts in the con...

    English: Illustration of wavefronts in the context of Snell’s law. (Photo credit: Wikipedia)

    Understand and use the terms amplitude, frequency, period, speed and wavelength

  1. Identify the different regions of the electromagnetic spectrum and describe some of their applications.
  1. Use the wave equation v = fλ.
  1. Recall that a sound wave is a longitudinal wave which can be described in terms of the displacement of molecules.
  1. Use graphs to represent transverse and longitudinal waves, including standing waves.
  1. Explain and use the concepts of wavefront, coherence, path difference, superposition and phase.
  1. Recognize and use the relationship between phase difference and path difference.
  1. Explain what is meant by a standing (stationary) wave, investigate how such wave is formed, and identify nodes and antinodes.
  1. Recognize and use the expression for refractive index 1μ2  = sin i/sin r = v1/v2 determine refractive index for a material in the laboratory, and predict whether total internal reflection will occur at an interface using critical angle.
  1. Investigate and explain how to measure refractive index.
  1. Investigate and explain how to measure the rotation of the plane of polarization.
  1. Investigate and recall that waves can be diffracted and that substantial diffraction occurs when the size of the gap or obstacle is similar to the wavelength of the wave.
  1. Explain how diffraction experiments provide evidence for the wave nature of elections.
  1. Discuss how scientific ideas may change over time, for example, our ideas on the particle/wave nature of electrons.
  1. Recall that, in general, waves are transmitted and reflected at an interface between media.
  1. Explain how different media affect the transmission/reflection of waves travelling from one medium to another.
  1. Explore and explain how a pulse-echo technique can provide details of the position and/or speed of an object and describe applications that use this technique.
  1. Explain qualitatively how the movement of a source of sound or light relative to an observer/detector gives rise to a shift in frequency (Doppler Effect) and explore applications that use this effect.
  1. Explain how the amount of detail in a scan may be limited by the wavelength of the radiations or by the duration of the pulses.
  1. Discuss the social and ethical issues that need to be considered, e.g., when developing and trailing new medical techniques on patients or when funding a space mission.
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Light wave or particle?

21 Aug
No. Name   of Scientist Year   Place Perspective Key   ideas
1 Democritus B.C  Ancient Greece Particle theory “atoms  swarmed into the observer’s eyes”
2 Empedocles B.C Ancient Greece Wave theory “ Objects becomes visible   when touched by light rays emitted by the object”
3 Plato B.C Ancient Greece Wave theory
4 Leonardo Da Vinci 15th century Italy Wave theory “Compared the light   reflection to echo”
5 Francesco Maria Grimaldi 1665 Italy Wave theory “ Paper  published in 1665 after his death “ worked   on diffraction supporting  La Da Vinci
6 Robert Hooke  and Boyle 1665 England Wave theory “ Compared light with   water waves” explained the colours were formed on the water due to oil film
English: Validity of several theories for peri...

English: Validity of several theories for periodic water waves, according to Le Méhauté (1976). The light-blue area is the range of validity of cnoidal wave theory; light-yellow for Airy wave theory; and the dashed blue lines demarcate the required order of Stokes’ wave theory. The light-gray shading gives the range extension by numerical approximations using fifth-order stream-function theory, for high waves (H > ¼ H breaking ). (Photo credit: Wikipedia)

Light!  Wave or particle

In the end of seventeenth century saw a fierce debate about the nature of light.  Newton compared light with a stream of particles and this was accepted for reflection and refraction could be explained using this model.  He also argued that if light were waves then it would not form the sharp image of the object. (He did not realise that the light wave were too small!)

 

No. Name   of scientist Year Place Perspective Key   ideas
7  Thomas Young 1802 England Wave   theory His   double slit experiment
8 Leon   Foucault 1853 France Wave   theory His   experimental value of speed of light gave a death blow to particle theory for   it required the light to travel faster in H2O then in N2.
9 Albert   Einstein 1905 Germany Particle   theory Photo   electric effect.

The dilemma was recreated and then it was resolved only after Louis de Broglie produced his theory of wave-particle duality. He received the Nobel Prize for the world had accepted his explanation of light as being both particle and wave!

 

This new discovery gave rise to quantum mechanics.

 

 

10 Albert   Einstein 1905 Germany Particle   theory Photo   electric effect.
11 Thomson England Particle   theory Cathode   rays
12 Max   Plank 1918 Germany Quantised Radiation Black   Body Radiation
13 Louis   De Broglie 1927 France Issue resolved Crystals do show diffraction when   illuminated by electrons as confirmed independently by Davisson and Thomson.

The dilemma was recreated and then it was resolved only after Louis de Broglie produced his theory of wave-particle duality. He received the Nobel Prize for the world had accepted his explanation of light as being both particle and wave!

 

 

This new discovery gave rise to quantum mechanics.

 

 

 

 

 

 

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Lights

Lights (Photo credit: cycloctopus)

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