Final answer:
The P wave characteristics include being smooth, rounded, no more than 2.5 mm in height, no more than 0.11 seconds in duration, and positive in specified leads. It represents atrial depolarization in the cardiac cycle.
Step-by-step explanation:
The characteristics of a normal P wave on an electrocardiogram (ECG) include being smooth and rounded, measuring no more than 2.5 mm in height, and lasting no more than 0.11 seconds in duration. It should also be positive in leads I, II, aVF, and V2 through V6. The P wave represents the depolarization of the atria as they pump blood into the ventricles. This is an essential part of the cardiac cycle, preceding atrial contraction by about 25 milliseconds. The P wave is an important indicator of atrial function and can reveal abnormalities such as atrial enlargement or arrhythmias.