Physics HL
Physics HL
5
Chapters
329
Notes
Theme A - Space, Time & Motion
Theme A - Space, Time & Motion
Theme B - The Particulate Nature Of Matter
Theme B - The Particulate Nature Of Matter
Theme C - Wave Behaviour
Theme C - Wave Behaviour
Theme D - Fields
Theme D - Fields
Theme E - Nuclear & Quantum Physics
Theme E - Nuclear & Quantum Physics
IB Resources
Theme C - Wave Behaviour
Physics HL
Physics HL

Theme C - Wave Behaviour

Unlocking Light Mysteries: The Double-Slit Experiment

Word Count Emoji
610 words
Reading Time Emoji
4 mins read
Updated at Emoji
Last edited on 5th Nov 2024

Table of content

Interference of light waves

  • Like sound waves, light waves and microwaves can interfere. This interference can be observed by shining a single light source through two thin vertical slits, an arrangement known as a double slit.
  • The phenomenon was first observed by English physicist and physician Thomas Young in 1801 and is known as double-slit interference or Young's slit experiment.

How does it work?

  • When a laser or lamp is used to shine light through the two slits, light falls on both slits and creates diffraction patterns.
  • If a laser is used, the light is already coherent, meaning the waves are in phase.
  • If a lamp is used, a single slit is placed before the double slit, making the light coherent by allowing only a small portion of the wavefront to pass through.
  • Each slit emits a cone of diffracted light, which is bounded by the central maximum of the diffraction pattern for that cone.
  • The region where the two diffracted beams intersect is where interference can occur. This is because interference requires two beams.

Interference pattern

  • When a screen is placed parallel to the plane of the slits in the interference region, a pattern of fringes appears on the screen.
  • These fringes, parallel to the orientation of the double slits, show an alternating bright–dark arrangement with equal spacing on the screen.
  • This pattern is similar to the alternating loud and soft regions of sound wave interference.

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IB Resources
Theme C - Wave Behaviour
Physics HL
Physics HL

Theme C - Wave Behaviour

Unlocking Light Mysteries: The Double-Slit Experiment

Word Count Emoji
610 words
Reading Time Emoji
4 mins read
Updated at Emoji
Last edited on 5th Nov 2024

Table of content

Interference of light waves

  • Like sound waves, light waves and microwaves can interfere. This interference can be observed by shining a single light source through two thin vertical slits, an arrangement known as a double slit.
  • The phenomenon was first observed by English physicist and physician Thomas Young in 1801 and is known as double-slit interference or Young's slit experiment.

How does it work?

  • When a laser or lamp is used to shine light through the two slits, light falls on both slits and creates diffraction patterns.
  • If a laser is used, the light is already coherent, meaning the waves are in phase.
  • If a lamp is used, a single slit is placed before the double slit, making the light coherent by allowing only a small portion of the wavefront to pass through.
  • Each slit emits a cone of diffracted light, which is bounded by the central maximum of the diffraction pattern for that cone.
  • The region where the two diffracted beams intersect is where interference can occur. This is because interference requires two beams.

Interference pattern

  • When a screen is placed parallel to the plane of the slits in the interference region, a pattern of fringes appears on the screen.
  • These fringes, parallel to the orientation of the double slits, show an alternating bright–dark arrangement with equal spacing on the screen.
  • This pattern is similar to the alternating loud and soft regions of sound wave interference.

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Dive deeper and gain exclusive access to premium files of Physics HL. Subscribe now and get closer to that 45 🌟

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