# Electromagnetic force interaction

As far as I know, the electromagnetic force only interacts on particles with electrical charge, but I was told that the electromagnetic force was involved in the following reaction:

$$\Sigma^0\rightarrow\Lambda^0+\gamma.$$

How can this be, when the electric charge of both the $\Sigma^0$ particle and the $\Lambda^0$ particle is $0$? Or is it another fundamental interaction that is involved in the reaction? Thank you.

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I guess it's because quarks have electric charge. –  jinawee Mar 24 '14 at 15:36
A hydrogen atom is one proton plus one electron, so its overall electric charge is zero. But even though hydrogen atoms are neutral, the electric force will bind two hydrogen atoms together to form molecular hydrogen, $H_2$. –  David H Mar 24 '14 at 15:41