Is the Photoelectric Effect Proof That Light Is a Particle?

[Drakkith]

A single wave (or wavefront) can have any energy as long as it's a multiple of hf.

 

[sss1]

Is it because a single wave is made of many photons and each individual photon has an energy E=hf?
So the energy of an individual photon is not quantised but the energy of a wave is quantised?

 

[Drakkith]

We're really just getting into semantics and what a 'single' wave is. It's not important. If an EM wave comes in, no matter if it has one or many 'waves' or 'wavefronts', its energy will be some integer multiple of hf.

So the energy of an individual photon is not quantised but the energy of a wave is quantised?

The photon IS the quantization of the wave. The wave is quantized and that shows up as a photon.

 

[sss1]

The photon IS the quantization of the wave. The wave is quantized and that shows up as a photon.

But a photon can have any energy it wants? Whereas the energy of a wave needs to be a multiple of hf?

 

[PeroK]

But a photon can have any energy it wants? Whereas the energy of a wave needs to be a multiple of hf?

That's the wrong way round. Classically the energy of a wave is not determined by its frequency. The Classical wave model cannot explain certain phenomena like the photoelectric effect.

So, you need to quantize the EM field and introduce quanta of that field, called photons.

White light is a mixture of frequencies. But, monochromatic light has a single frequency and can only deliver energy in discrete quanta, which depend on the frequency.

Light is neither a classical wave nor a classical particle. It's a product of the quantized EM field.

 

[Drakkith]

But a photon can have any energy it wants? Whereas the energy of a wave needs to be a multiple of hf?

No. The photon's energy is determined by the frequency of the wave.