# De broglie frequrency

1. Feb 24, 2015

### ChAshutosh

As we know de broglie wavelength is λ = h/p and f = E/h
λ = h/p
v/f = h/mv as f*λ=v

then

f = mv^2/h

but it should f = E/h and E=1/2*mv^2

2. Feb 24, 2015

### Suraj M

When you say $$E= \frac{1}{2} mv^2$$ you are considering only kinetic energy, do you think that, it is the only type of energy the body has, whose wave motion is also being is considered?

3. Feb 24, 2015

### bhobba

Remember De-Broglies ideas are a mishmash of quantum and relatvistic ideas. Best to forget about them - they have long since been consigned to the dustbin of history. But since its relatvistic E is not the classical 1/2 mv^2:
http://hyperphysics.phy-astr.gsu.edu/hbase/debrog.html

Thanks
Bill

4. Feb 24, 2015

### Suraj M

Bhobba, is there noway of achieving E = mv² by adding the energy due to SHM of each particle along the wave, to the KE?

5. Feb 24, 2015

### bhobba

I don't know what you mean by that.

Like most I have read about the De-Broglie theory and seen the equations. They are an inconsistent mish-mash eg what's the wavelength of a stationary particle - and by frame jumping you can always go to a frame where its stationary. Because of that I tend to not get worried about manipulations involving them - it's wrong anyway.

In QM the KE of a free particle is 1/2 mV^2 where V is the velocity operator.

Interestingly one can actually prove that from symmetry in QM - but that is another story.

Thanks
Bill

6. Feb 24, 2015

### Suraj M

I mean the particles would have an extra amount of energy of $½m \omega^2 A^2$ can we use that?

7. Feb 24, 2015

### bhobba

You lost me.

Can you explain what your terms mean?

Thanks
Bill

8. Feb 24, 2015

### Suraj M

The regular SHM terms! $\omega$ = 2$\pi /T$ ; A = amplitude of the wave

9. Feb 24, 2015

### bhobba

I think you are trying to introduce concepts from the quantum harmonic occilator used in QFT. QFT is a whole new ball game not compatible with ordinary QM.

The energy in QM is actually based on the Galilaen transformations while QFT is based on the Lorentz transformations.

Thanks
Bill