Question

Question #8f7d2

Answer 1

Electric charge can neither be created or destroyed.

In ordinary experience this means that if we start with some number of electrons (negatively charged) and protons (positively charged), we will always have the same number of electrons and protons.

Mathematically stated, `Q_f` the final charge in a system is equal to the initial charge `Q_i`. Unless charge has been added or removed from the system, `Q_"IN"` or `Q_"OUT"`.

`Q_"f" = Q_i + Q_"IN" - Q_"OUT"`

In more exotic interactions such as radioactive decay, it is possible for the nucleus of an atom to absorb an electron (called Electron Capture) and transform one of its protons into a neutron.

`p + e^"-" = n + nu_e`

Here the interaction also results in an electron neutrino (`nu_e`) which conserves a property known as lepton family number.

Also, in the annihilation of matter with antimatter, two opposite charges come together and both are destroyed and converted into some other particle. The science fiction writers would insert the term "pure energy" here. In fact, it is typical for such particles to simply form two gamma rays, each carrying half of the total mass energy of the two particles.

In the case of the interaction between an electron (`e^"-"`) and a positron (`e^"+"`) the result is:

`e^"+" + e^"-" = gamma + gamma`

On the left side you had one positive and one negative charge. On the right side you have two un-charged photons. The total charge before and after the interaction is zero.