A student builds an electromagnet using a battery and coiling wire around a nail. The student observes that the electromagnet attracts pins.

Wind will blow from one direction to another.

Density and pressure

Each calcium ion has a charge of +2, which can also be written as ca2+. if those ions move out of the neuron and no other ions are moving, the neuron would lose the positive charge associated with those ions and become more negatively charged.