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Wavenumber Formula:
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Wavenumber is a property of a wave that is defined as the number of wavelengths per unit distance. In spectroscopy, it represents the spatial frequency of a wave and is typically measured in reciprocal meters (m⁻¹).
The calculator uses the wavenumber formula:
Where:
Explanation: This formula converts energy to wavenumber using fundamental physical constants, showing the relationship between a photon's energy and its wavenumber.
Details: Wavenumber is particularly important in spectroscopy and quantum mechanics as it provides a direct measure of photon energy that is proportional to frequency. It's commonly used in infrared spectroscopy where molecular vibrations are reported in cm⁻¹.
Tips: Enter energy in joules, Planck's constant in J·s, and speed of light in m/s. Default values are provided for Planck's constant and the speed of light based on their standard values.
Q1: What's the difference between wavenumber and wavelength?
A: Wavelength is the distance between successive wave peaks, while wavenumber is the number of waves per unit distance (the reciprocal of wavelength).
Q2: Why is wavenumber used in spectroscopy instead of wavelength?
A: Wavenumber is directly proportional to energy and frequency, making spectral plots linear in wavenumber space, which is more convenient for analysis.
Q3: What are typical wavenumber values in spectroscopy?
A: In infrared spectroscopy, wavenumbers typically range from 400-4000 cm⁻¹. To convert from m⁻¹ to cm⁻¹, divide by 100.
Q4: Can I calculate energy from wavenumber?
A: Yes, you can rearrange the formula: \( E = \text{Wavenumber} \times h \times c \).
Q5: Why are Planck's constant and speed of light included as inputs?
A: While these are physical constants, they're included as inputs to allow for calculations with different precision values or in different unit systems if needed.