# B Magnetic Field from Protons vs Electrons

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1. Sep 12, 2018

### General Scientist

If an electron is moving in a circle in a magnetic field, it produces a magnetic field in accordance to the right hand rule. If a proton is moving in a circle in a magnetic field, would it produce a magnetic field in accordance to the left hand equivalent to the right hand rule.

2. Sep 12, 2018

### Master1022

You are correct as magnetic fields are created by moving charges, and the example would satisfy the criteria. Although, I assume it would be tiny compared to the surrounding magnetic field. The right hand rule would work for a proton.

3. Sep 12, 2018

The magnetic field for both is described by Biot-Savart's law. $\vec{B}=\frac{\mu_o}{4 \pi} \frac{q \vec{v} \times\vec{r}}{|\vec{r}|^3}$. With a negative charge on the electron, its magnetic field is opposite the direction given by $\vec{v} \times \vec{r}$.

4. Sep 12, 2018

### General Scientist

So the positive charge of a proton would mean the magnetic field is just $\vec{v} \times \vec{r}$?

5. Sep 12, 2018

See the part I added to post 3=the formula for $\vec{B}$.