Light Comes in Photons
Part of the Optics, Waves and Modern Physics section of Coddy's Physics journey. Lesson 34 of 53.
Light is absorbed and given out in packets: photons.
E = hf = hc / λ
h = 6.63 × 10⁻³⁴ J·s. Higher frequency (violet): more energy per photon. Brighter: more photons.
1 eV = 1.6 × 10⁻¹⁹ J. Green light (500 nm): about 2.5 eV per photon.
Challenge
What is the energy E of a photon of green light of wavelength 500 nm, in eV?
Try it yourself
Test yourselfThis lesson includes a short quiz. Start the lesson to answer it and track your progress.
All lessons in Optics, Waves and Modern Physics
1Reflection and Refraction
Reflection of LightThe Refractive IndexSnell's LawTotal Internal ReflectionDispersionApparent DepthRecap - Optical Fiber4Mechanical Waves
What a Wave IsTwo Graphs of a WaveWhen Pulses MeetInterferenceStanding WavesHarmonicsRecap - Guitar String7Photons
Light Comes in PhotonsThe Photoelectric EffectEinstein's EquationStopping VoltageCounting PhotonsRecap - Solar Cell