Calculator inputs
Formula used
E = hν
E = hc/λ
E(eV) = E(J) / e
ν = c/λ
ṽ(cm⁻¹) = 1 / λ(cm)
p = h/λ
Energy per mole = E × NA
Equivalent temperature = E / kB
Wavelength in medium = λ / n
Here, h is Planck's constant, c is light speed, e is the elementary charge, NA is Avogadro's constant, and n is refractive index.
How to use this calculator
- Select the input mode that matches your known quantity.
- Enter the value and choose its correct unit.
- Set refractive index if the photon moves through a medium.
- Optionally enter photon count or chemical amount in moles.
- Press calculate to view eV, joules, wavelength, momentum, and related outputs.
- Use the graph and export buttons to save or review results.
Example data table
| Known input | Value | Derived energy | Spectral region |
|---|---|---|---|
| Wavelength | 500 nm | 2.479684 eV | Visible |
| Frequency | 600 THz | 2.481405 eV | Visible |
| Wavenumber | 20,000 cm⁻¹ | 2.479684 eV | Visible |
| Energy | 10 eV | 10.000000 eV | Ultraviolet |
FAQs
1. What does this calculator primarily return?
It returns photon energy in electronvolts first, then shows joules, wavelength, frequency, wavenumber, momentum, molar energy, temperature equivalent, and medium-adjusted wavelength.
2. Can I start from wavelength or frequency?
Yes. You can begin with wavelength, frequency, wavenumber, or direct energy. The calculator converts the chosen input into a complete set of related photon properties.
3. Why is refractive index included?
Refractive index changes phase velocity and wavelength inside a medium. Photon energy stays the same, but the in-medium wavelength becomes shorter as refractive index increases.
4. Does photon energy change inside a medium?
No. For the same photon, energy remains linked to frequency, which does not change at a boundary. Only speed and wavelength in the medium change.
5. What is the meaning of energy per mole?
Energy per mole tells you the total energy carried by Avogadro's number of identical photons. It is useful in chemistry, spectroscopy, and photochemical comparisons.
6. Why does the graph use wavelength?
Wavelength offers an intuitive horizontal scale for spectroscopy. The graph plots energy against wavelength and marks your result, making inverse behavior easy to inspect.
7. Can I export the calculated result?
Yes. Use the CSV button to save numeric rows and the PDF button to capture the result section for reports, notes, or lab documentation.
8. Which fields are optional?
Photon count and amount in moles are optional. They extend the result by estimating total photon-bundle energy and total energy for the entered amount.