Unlike phantom power, bias does not require a balanced circuit. Bias supplies power to a Junction Field Effect Transistor (JFET) connected to the output of an electret condenser mic element. The JFET acts as an impedance converter that is a necessity in any microphone design that uses a condenser element.
Iodine atoms have 53 electrons and the shell structure is 2.8.18.18.7. The ground state electron configuration of ground state gaseous neutral iodine is [Kr].4d10.5s2.5p5 and the term symbol is 2P3/2.
Electron configuration was first conceived under the Bohr model of the atom, and it is still common to speak of shells and subshells despite the advances in understanding of the quantum-mechanical nature of electrons.