Optical spectrometer experiment

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SUMMARY

The discussion centers on conducting an experiment to calculate Planck's constant using LEDs and optical components. The proposed setup involves a variable DC supply, voltmeter, LED, spectrometer, and diffraction grating. A key inquiry is whether a triangular prism can effectively replace the diffraction grating for wavelength determination through refraction. The consensus indicates that using a prism is feasible, provided that the energy gap (E_g) of the LED is known to construct a calibration curve based on minimum deviation angles.

PREREQUISITES
  • Understanding of Planck's constant and its significance in physics.
  • Knowledge of LED energy gaps (E_g) and their relation to wavelength.
  • Familiarity with optical components such as diffraction gratings and prisms.
  • Basic principles of light refraction and spectrometry.
NEXT STEPS
  • Research the construction of calibration curves for optical experiments.
  • Learn about the properties and applications of triangular prisms in optics.
  • Investigate methods for measuring minimum deviation angles with a spectroscope.
  • Explore the relationship between energy gaps of LEDs and their emitted wavelengths.
USEFUL FOR

Physics students, optical engineers, and hobbyists interested in experimental physics and optical measurements will benefit from this discussion.

LoD
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Hi,
I need to do an experiment to calculate Planck's constant from LEDs. Basically what I'm intending to do is a fairly simple variable dc supply->voltmeter->LED->spectrometer->diffraction grating->my eye type setup. I know how to do that, but the trouble is I'll need to track down a diffraction grating. What I'd like to know is, would it be possible to use a triangular prism instead and work out the wavelength using refraction? In theory it should, but would it in practice?
Thanks
 
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Assuming that you know the energy gap [itex]E_g[/itex] of the LED you can construct a calibration curve with the prism by plotting the minimum deviation angles, measured with the spectroscope, for various spectral lines, against their wavelengths. Use this curve to determine the wavelength of the LED.
 

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