Energy of a photon

Electromagnetic radiation evidence they're waves

They can be diffracted, they show interference effects

Wave-particle duality

Behave like both waves and particles

Wave-particle duality of electromagnetic waves

They travel through space as waves but interact with matter as photons

Photon

A packet of electromagnetic energy or one quantum of electromagnetic energy

How to observe the partice-like behaviour of electromagnetic waves?

Placing a Geiger counter in front of a source emitting gamma rays, each click it registers is the physical detection of a single gamma-ray photon

E = hf

Energy of photon = planks constant x frequency

E = hc / λ

Energy of a photon = planks constant x the speed of light / wave length

Photon relationship with frequency

Directly proportional (E = hc / λ)

Photon relationship with wavelength

Inversely proportional (E = hc / λ)

The electronvolt (eV)

The energy gained by an electron travelling through a potential difference of 1 volt

Converting eV - J

Multiply by 1.6x10^-19

Why is the electronvolt useful?

For dealing with particles and photons when the energy in joules is very small

Once LEDs reach threshold voltage

They begin to emit light, as the threshold voltage the energy lost by a single electron reappears as the energy of a single photon of light