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Double-Slit interference

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Ria Tiwary

Thomas Young's double-slit experiment demonstrated that light has wave-like properties by showing that light passing through two slits will produce an interference pattern of bright and dark fringes on a screen. The experiment found that the distance between fringes is determined by the wavelength of light and the distance between the slits and screen. Increasing the wavelength or distances between slits or screen decreases the fringe spacing. This relationship can be used to calculate unknown wavelengths from measured distances. For example, in an experiment using sodium light with 0.3mm slits 1.2m from a screen showing 2.4mm spaced fringes, the wavelength is calculated to be 589nm.

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Double-Slit Interference By: Ria Tiwary Student Number: 34003146 Physics 101
Thomas Youngs Experiment Thomas Youngs double-slit experiment was conducted to prove that light has wave-like properties, as well as having photon particles.
The condition for a bright fringe to appear on the optical screen: dsin慮=n了 Where d is the distance between the two slits and n is an integer. The distance between 2 successive fringes (on the optical screen): s=了D/d Where D is the distance between the screen and the slits.
How to Make Sense of the Formulae An increase in the wavelength of the light results in: increase in number of fringes on screen and decrease in distance between fringes An increase in the distance between slits results in: increase in number of fringes on screen and decrease in distance between fringes An increase in the distance between the screen and the slits results in: increase in number of fringes on screen and decrease in distance between fringes
Application of Double-Slit Interference Double-slit interference allows us to measure the wavelength of lights using Youngs equation: 了 = y d / (m L) d: distance between slits L: distance from slits to screen y: distance from central antinode to 4th antinode m: order value
Sample Question In a two-slit apparatus the slits are 0.3 mm apart. Fringes in sodium are observed at a distance of 1.2 m from the slits. The separation of the fringes is 2.4 mm. What is the wavelength of sodium light?
Solution m106 m1.2/m)103.0104.2( *1/ L)(m/dy 7 43 器 器器器 Ldy

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Double-Slit interference

  • 1. Double-Slit Interference By: Ria Tiwary Student Number: 34003146 Physics 101
  • 2. Thomas Youngs Experiment Thomas Youngs double-slit experiment was conducted to prove that light has wave-like properties, as well as having photon particles.
  • 3. The condition for a bright fringe to appear on the optical screen: dsin慮=n了 Where d is the distance between the two slits and n is an integer. The distance between 2 successive fringes (on the optical screen): s=了D/d Where D is the distance between the screen and the slits.
  • 4. How to Make Sense of the Formulae An increase in the wavelength of the light results in: increase in number of fringes on screen and decrease in distance between fringes An increase in the distance between slits results in: increase in number of fringes on screen and decrease in distance between fringes An increase in the distance between the screen and the slits results in: increase in number of fringes on screen and decrease in distance between fringes
  • 5. Application of Double-Slit Interference Double-slit interference allows us to measure the wavelength of lights using Youngs equation: 了 = y d / (m L) d: distance between slits L: distance from slits to screen y: distance from central antinode to 4th antinode m: order value
  • 6. Sample Question In a two-slit apparatus the slits are 0.3 mm apart. Fringes in sodium are observed at a distance of 1.2 m from the slits. The separation of the fringes is 2.4 mm. What is the wavelength of sodium light?