De Broglie Wavelength and Particle Velocity
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Questions and Answers

What is the speed range of the cathode ray particles as determined by Thomson's experiment?

  • 0.1 to 0.2 times the speed of light (correct)
  • More than 0.2 times the speed of light
  • Equal to the speed of light
  • Less than 0.1 times the speed of light

    • What did Thomson's observation about the value of e/m being independent of the cathode material or the gas suggest?

  • The need for specific cathode materials for experiments
  • The uniqueness of each cathode material
  • The variation in e/m based on cathode material
  • The universality of the cathode ray particles (correct)

    • In 1887, what was found about certain metals when irradiated by ultraviolet light?

  • They emitted negatively charged particles with small speeds (correct)
  • They remained unchanged
  • They emitted positively charged particles
  • Their temperature increased significantly

    • What did the observation about metals emitting negatively charged particles when heated to high temperatures establish?

    <p>The identical nature of these particles to cathode ray particles</p> Signup and view all the answers

    What did J.J. Thomson name the negatively charged particles discovered through his experimental investigations?

    <p>Electrons</p> Signup and view all the answers

    For his discovery of electrons and contributions to the conduction of electricity by gases, in which year was J.J. Thomson awarded the Nobel Prize in Physics?

    <p>1906</p> Signup and view all the answers

    What does it mean when the text states that an electron's position uncertainty is infinite?

    <p>The electron is located in a finite region of space.</p> Signup and view all the answers

    How does a wave packet differ from a wave with a fixed wavelength?

    <p>A wave packet extends over some finite region of space, while a fixed wavelength wave extends all over space.</p> Signup and view all the answers

    According to de Broglie's relation, what happens to the momentum of an electron associated with a wave packet?

    <p>The momentum has an uncertainty and spreads out.</p> Signup and view all the answers

    What property of a wave packet allows it to have an uncertainty in both position and momentum?

    <p>Extending over some finite region of space</p> Signup and view all the answers

    How do the concepts of de Broglie relation, Born's probability interpretation, and wave packets relate to Heisenberg's uncertainty principle?

    <p>They form the basis for explaining Heisenberg's uncertainty principle.</p> Signup and view all the answers

    How does the depiction of an electron as a localised wave packet differ from that of an extended wave with fixed wavelength?

    <p>The localised wave packet is spread over a finite region, while the extended wave is localized.</p> Signup and view all the answers

    Who formulated the laws of refraction in 1621?

    <p>Snell</p> Signup and view all the answers

    When did Huygens propose that light consists of waves?

    <p>Around 1650-60</p> Signup and view all the answers

    Which model of light was merely a philosophical proposal without scientific experiments or arguments?

    <p>Descartes' particle theory</p> Signup and view all the answers

    What did both Descartes and Newton's models of light manage to explain?

    <p>All the known properties of light</p> Signup and view all the answers

    Which scientist extended Descartes' particle model and built it up as a scientific theory?

    <p>Newton</p> Signup and view all the answers

    What was the speed of light concluded to be by scientists before accurate measurement was possible?

    <p>Higher than the limit of their measurement</p> Signup and view all the answers

    What does |A|^2∆V represent in the context of matter waves?

    <p>Probability of the particle being found in a small volume around a point</p> Signup and view all the answers

    In the context of matter waves, what does a large intensity indicate about the probability of finding a particle?

    <p>Greater probability of finding the particle</p> Signup and view all the answers

    What is the formula for de Broglie wavelength of a moving particle?

    <p>$\lambda = \frac{h}{p}$</p> Signup and view all the answers

    Given an electron moving three times as fast as another particle, what is the ratio of their de Broglie wavelengths?

    <p>$1.813 × 10^{-4}$</p> Signup and view all the answers

    What determines the mass of a moving particle in the context of de Broglie wavelength?

    <p>$\frac{h}{\lambda v}$</p> Signup and view all the answers

    When an electron is accelerated through a potential difference, what happens to its de Broglie wavelength?

    <p>Increases substantially</p> Signup and view all the answers

    Who discovered double refraction of light in some crystals in 1669?

    <p>Bartholinus</p> Signup and view all the answers

    What theory did Huygens use to explain the double refraction of light in crystals?

    <p>Wave theory</p> Signup and view all the answers

    Which experiment performed in 1801 demonstrated interference fringes and supported the wave theory of light?

    <p>Young's double-slit experiment</p> Signup and view all the answers

    What phenomenon, observed around 1810, could be naturally explained by the wave theory of light?

    <p>Polarisation</p> Signup and view all the answers

    Why was Newton’s particle model of light preferred over the wave model for over a century?

    <p>Simplicity and contemporary physics influence</p> Signup and view all the answers

    What value was determined for the speed of light in vacuum in the nineteenth century through accurate experiments?

    <p>$3 × 10^8$ m/s</p> Signup and view all the answers

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