# Size of proton, neutron and electron

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1. Nov 5, 2016

### Lucy11802

1. The problem statement, all variables and given/known data
So my teacher set us half term homework and one of the questions was state the relative size of a proton a neutron and an electron

2. Relevant equations
3. The attempt at a solution
Im a bit confused because everyone in my class got
Proton: 1
Neutron: 1
Electron: negligible
But i got-
Proton: 0.84 fermatons (idk if thats spelt right)
Neutron: 0.84 fermatons
Electron: The size of its wave function

Im confused and need a bit of help- im in year 9 so im not reall hugley educated.

2. Nov 5, 2016

### Staff: Mentor

I guess you mean femtometer (sometimes called Fermi).
That is a problematic approach, because it means the size of the electron depends on where it is. If you want to use this approach, then you should also consider wave functions for protons and neutrons.

The question was about relative sizes. 0.84 femtometer is the absolute size.

3. Nov 5, 2016

### Lucy11802

Oh okay thanks, so should i just make the size less accurate and change the electron one then?

4. Nov 5, 2016

### Staff: Mentor

What do you mean by "less accurate"?

If the electron has an intrinsic size (in the same way as proton and neutron have a size), it has to be extremely tiny.

5. Nov 5, 2016

### Staff: Mentor

You are asked for the relative size, i.e., compared to each other. If you are twice as tall as your little sister, then your relative sizes are 2 and 1 (or 1 and 1/2), whatever your heights are in meters.