A(n) potential is the brief wave of positive electrical charge that sweeps down an axon.

The answer to your question is "Action Potential". An action potential is the brief wave of positive electrical charge that sweeps down an axon. This is a fundamental process in the transmission of information within the nervous system. Here are the steps of how it works:

1. Resting State: The axon is in a resting state with a negative charge inside relative to the outside. This is due to the distribution of ions including sodium and potassium.

2. Depolarization: A stimulus triggers the opening of some sodium channels. Sodium ions flow into the axon, causing a shift towards a positive charge inside the axon. This is the start of the action potential.

3. Rising Phase: As the inside of the axon becomes more positive, more sodium channels open. This causes an even greater influx of sodium ions and a rapid increase in the positive charge inside the axon.

4. Falling Phase: At the peak of the action potential, sodium channels close and potassium channels open. Potassium ions flow out of the axon, causing the inside of the axon to become more negative again.

5. After-Hyperpolarization: The outflow of potassium ions briefly causes the inside of the axon to be more negative than it is at rest. The potassium channels then close.

6. Return to Resting State: The sodium-potassium pump restores the distribution of ions to their resting state distribution, ready for the next action potential.