Scientists use i to represent magnetic fields

Explanation:Image result for how are the atomic number and protons related

The atomic number or proton number (symbol Z) of a chemical element is the number of protons found in the nucleus of every atom of that element. ... It is identical to the charge number of the nucleus. In an uncharged atom, the atomic number is also equal to the number of electrons.

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.