Final answer:
The voltage across a cell membrane at rest is typically -70mV. This is known as the resting membrane potential, which is maintained by the distribution of ions and the activity of proteins.
Step-by-step explanation:
The voltage across a cell membrane at rest is typically around -70mV. This value is known as the resting membrane potential, which refers to the difference in charge across the membrane of a cell when it is not actively transmitting signals.
The resting membrane potential is maintained by the distribution of ions across the membrane and the activity of proteins such as leakage channels and the Na+/K+ pump. These proteins help to maintain the balance of ions inside and outside of the cell.