Wavelength to Color Calculator

Q: What is wavenumber?

Wavenumber = 1/lambda (cm^-1). Common unit in IR spectroscopy. 1000 cm^-1 = 10 micron IR radiation (molecular vibration).

Q: How does energy relate to chemical bond breaking?

Typical bond energy: C-H: 413 kJ/mol. UV photons (300 nm): 399 kJ/mol, enough to break C-H! Explains UV photodegradation.

Q: What is the photoelectric effect?

Photons with E > work function eject electrons from metal. Einstein won 1905 Nobel Prize for explaining this using quantum of light (photon).

Convert wavelength of light to color, frequency, energy (eV and kJ/mol), and wavenumber. Find electromagnetic spectrum position for any wavelength from UV to infrared.

🌈 Spectroscopy📐 E = hc/λ🧪 Chemistry

Wavelength λ (nm)

Please enter valid values.

Formula & Reference

Variable	Symbol	Formula	Units
Wavelength to Color Calculator	—	E = hc/λ	eV or kJ/mol

Step-by-Step Examples

Example 1

Blue Light

Lambda = 450 nm.

E = hc/lambda = 6.626x10^-34 x 3x10^8/450x10^-9 = 4.42x10^-19 J
eV = 4.42x10^-19/1.602x10^-19 = 2.76 eV
kJ/mol = 4.42x10^-19 x 6.022x10^23/1000 = 266 kJ/mol

✓ Blue light: 2.76 eV per photon, 266 kJ/mol

Example 2

UV-A Radiation

Lambda = 365 nm.

E = 6.626x10^-34 x 3x10^8/365x10^-9 = 5.45x10^-19 J
eV = 3.40 eV, kJ/mol = 328 kJ/mol
UV-A region: 315-380 nm

✓ UV-A: 3.40 eV, 328 kJ/mol

Example 3

Infrared at 1000 nm

Lambda = 1000 nm.

E = 6.626x10^-34 x 3x10^8/10^-6 = 1.99x10^-19 J
eV = 1.24 eV, kJ/mol = 119.7 kJ/mol
Near IR: 740-1000 nm

✓ Near IR: 1.24 eV, 119.7 kJ/mol

Real-World Applications

🔬

Spectroscopy

Wavelength determines which molecular transitions are excited: UV/Vis (electronic), IR (vibrational).

☂️

Sunscreen

UV-A (315-400 nm) and UV-B (280-315 nm) protection. SPF covers UV-B primarily.

🛰️

Remote Sensing

Satellites measure reflected/emitted light at specific wavelengths to identify materials on Earth.

💡

LED Technology

LED wavelength (color) determined by semiconductor bandgap energy. E = hf = eV.

Common Mistakes to Avoid

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Convert nm to meters for calculation

lambda must be in meters for E = hc/lambda. 450 nm = 450 x 10^-9 m = 4.50 x 10^-7 m.

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eV vs kJ/mol

eV is energy per photon. kJ/mol is energy per mole of photons (x Avogadro). Both useful in different contexts.

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Visible light: 380-740 nm approximately

Violet: 380-440, Blue: 440-490, Green: 490-565, Yellow: 565-590, Orange: 590-625, Red: 625-740 nm.

Frequently Asked Questions

What is the visible spectrum? ▾

Human vision: ~380-740 nm. ROY G BIV: Red-Orange-Yellow-Green-Blue-Indigo-Violet. Colors determined by wavelength.

What are photon energies by region? ▾

Gamma: >10 MeV. X-ray: keV range. UV: 3-12 eV. Visible: 1.6-3.2 eV. IR: <1.6 eV. Microwave: much less.

What is wavenumber? ▾

Wavenumber = 1/lambda (cm^-1). Common unit in IR spectroscopy. 1000 cm^-1 = 10 micron IR radiation (molecular vibration).

How does energy relate to chemical bond breaking? ▾

Typical bond energy: C-H: 413 kJ/mol. UV photons (300 nm): 399 kJ/mol, enough to break C-H! Explains UV photodegradation.

What is the photoelectric effect? ▾

Photons with E > work function eject electrons from metal. Einstein won 1905 Nobel Prize for explaining this using quantum of light (photon).

Related Chemistry Calculators

Formula Explorer connections

Interpretation: This relationship uses electronic structure, bonding or molecular geometry to predict a chemical property or structural descriptor. Assumption: The model may be an approximation; resonance, solvent, coordination environment, conformation and experimental conditions can affect real molecules.

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