When to use this calculator
Calculate the energy of a photon from its vacuum wavelength. Uses exact SI values for Planck’s constant and vacuum light speed.
Explore the optics & quantum relationships calculators for other questions in this topic. For a related calculation, use the Photon Frequency Calculator: Convert a vacuum light wavelength into electromagnetic frequency.
PUTTING IT INTO PRACTICE
Photon Energy: a worked example
The values below are an illustrative example, not a recommendation. Replace them with measurements or assumptions that match your question.
| Input | Example value |
|---|---|
| Vacuum wavelength (nm) | 500 |
| Result | 3.972892e-19 J |
- Check the input labels and enter the example values above.
- Apply the relationship: Photon energy = h × c/wavelength.
- The result is 3.972892e-19 J, rounded for display.
How to interpret your result
Uses exact SI values for Planck’s constant and vacuum light speed.
Use the stated sign convention for lenses and angles measured to the normal for refraction. Vacuum wavelength differs from wavelength inside a material. These models do not account for every optical aberration or material response.
Frequently asked questions
Why can a refracted-angle calculation have no real result?
When Snell’s-law sine exceeds one, the ideal ray model predicts total internal reflection rather than a real transmitted angle.
When is the photon energy calculator useful?
Calculate the energy of a photon from its vacuum wavelength. Uses exact SI values for Planck’s constant and vacuum light speed.
How do I use the photon energy calculator?
Enter vacuum wavelength (nm). The result updates automatically. Use the units shown beside each input; the example values illustrate the method.
Which formula does this calculator use?
Photon energy = h × c/wavelength.
What should I check before using the result?
Uses exact SI values for Planck’s constant and vacuum light speed.
How are results rounded?
Scalar numbers display up to six decimal places, with scientific notation for very large or small values. Text, fraction, date and schedule outputs use the format described on the tool. Intermediate calculations use JavaScript floating-point arithmetic. Keep sensible precision for your measurements.
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