Equation and purpose
Energy of photon from frequency or wavelength.
\[E = h\nu = \frac{hc}{\lambda}\]
Energy of photon from frequency or wavelength.
REARRANGEMENTS
$\lambda=hc/E$
Dimensional check: J·s·Hz = J ✓
Variables and units
| Symbol | Quantity | Unit | Notes |
|---|---|---|---|
| E | E | — | — |
| h | h | — | — |
| ν | ν | — | — |
| λ | λ | — | — |
| c | c | — | — |
Conditions and limitations
EM wave in vacuum.
Worked example
λ=500 nm → E≈3.98×10⁻¹⁹ J.
Photon Energy
Energy of photon from frequency or wavelength.
Equation
Inline: $E = h\nu = \frac{hc}{\lambda}$$
Variables
| Symbol | Quantity | Unit | Notes |
|---|---|---|---|
| photon energy | J | — | |
| Planck constant | J·s | — | |
| frequency | Hz | — | |
| wavelength | m | — | |
| speed of light | m·s⁻¹ | — |
Conditions and limitations
EM wave in vacuum.
Rearrangements
Dimensional check: J·s·Hz = J ✓
Worked example
λ=500 nm → E≈3.98×10⁻¹⁹ J.
Steps: write equation → substitute with units → check dimensional consistency → report with correct significant figures.
Common errors
- Using λ in nm without conversion
Related resources
- atomic-structure topic
- Calculators — linked only when a real calculator implements this formula.
- Constants — sourced constants with version when values are required.
Sources
- NIST Physical Constants 2022 — CODATA.
Reviewed 2026-08-21 by Editorial Team; due 2027-08-21.
Common errors
- Using λ in nm without conversion
RELATED FORMULAS
C
Chemistry Fundamentals Editorial TeamAuthor
E
Editorial Review BoardReviewer
Editorial Team — transparent review placeholder
Reviewed August 21, 2026
SOURCES
- [nist-2022]NIST Physical Constants 2022 (2022). NISThttps://physics.nist.gov/constants