Photon Energy Calculator (E=hf)
Calculate the energy of a photon from its frequency using the Planck equation (E = h·f). Fundamental in quantum physics, optics and spectroscopy.
E (J)
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Photon energy from frequency: E = h·f
Frequency alone sets a photon's energy: E = h·f = h·c/λ, where h = 6.626·10⁻³⁴ J·s is Planck's constant and c = 3·10⁸ m/s. To go from joules to electronvolts, divide by 1.602·10⁻¹⁹. Take a visible photon at f = 5.45·10¹⁴ Hz (λ ≈ 550 nm, green); it carries E ≈ 3.6·10⁻¹⁹ J ≈ 2.25 eV. Push the frequency up into the UV and the photons get more energetic, enough to ionize matter. Drop it into the infrared and they carry less, mostly just heating things. Back in 1905 Einstein explained the photoelectric effect (which won him the Nobel in 1921) by showing that only photons above the work function knock electrons loose, and that light energy comes in quanta.
Applications
Solar panels, where silicon's 1.1 eV band gap pins the cutoff wavelength at roughly 1100 nm. Atomic and molecular spectroscopy. LEDs, whose emitted color tracks the semiconductor's band gap. You also find it behind CCD and CMOS sensors, lasers, photomultipliers and ionizing-radiation dosimetry.
FAQ
What's a typical visible-photon energy? It runs from about 1.7 eV (red, λ ≈ 700 nm) up to 3.1 eV (violet, λ ≈ 400 nm). Green at 550 nm lands near 2.25 eV.
Does a brighter beam mean each photon has more energy? No. Brightness only controls how many photons arrive per second. What each one carries still comes down to frequency, and that was Einstein's key insight.
Why does silicon's 1.1 eV band gap matter for solar cells? Any photon below 1.1 eV (infrared past 1100 nm) can't lift an electron across the gap, so its energy is simply lost as heat. That's what caps the efficiency of single-junction silicon.
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Calculate the work (energy) consumed in punching or sheet cutting, W = (k·F·t) ÷ 1000, from the penetration factor k (~0.3-0.6, the fraction of thickness the punch travels shearing before fracture), the cutting force F (N) and the sheet thickness t (mm); the result is in joules. While the cutting FORCE sets the press tonnage, the WORK sets the ENERGY the press must deliver in the stroke — a distinct and equally important parameter, especially in eccentric and friction presses that store energy in a flywheel. The factor k appears because the cut does not consume maximum force over the full thickness: the punch penetrates shearing, force rises to a peak, then drops as the material FRACTURES abruptly (the fracture propagates and separates the material before the punch crosses the whole thickness). So the work is only a fraction (k) of the maximum-force × thickness product. Knowing the work is essential to size the press flywheel and motor (which must replenish the energy between strokes) and to avoid heavy cuts 'stalling' the press from lack of stored energy. Enter the penetration factor, cutting force and thickness.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.