Final answer:
The voltage difference across a cell membrane is called membrane potential. Membrane potential is the result of the separation of charges, with the inside of the membrane being relatively negative and the outside being relatively positive.
Step-by-step explanation:
The voltage difference across a membrane of a cell is called membrane potential. Membrane potential is the result of the separation of charges, with the inside of the membrane being relatively negative and the outside being relatively positive. This separation of charges creates an electrical potential energy that is important for the conduction of electrical impulses along nerve cells.