Final answer:
The T wave on an ECG represents ventricular repolarization, which marks the beginning of ventricular relaxation or diastole in the heart's cycle.
Step-by-step explanation:
The T wave of an ECG corresponds to ventricular diastole. The cardiac cycle includes several stages, each represented by different waves on an ECG trace. The P wave is associated with atrial depolarization, leading to atrial contraction (atrial systole). The QRS complex represents ventricular depolarization, which precedes ventricular contraction (ventricular systole). Finally, the T wave is indicative of ventricular repolarization, marking the beginning of ventricular relaxation or diastole. Understanding the relationship between ECG components and the cardiac cycle is crucial for interpreting heart function.