Final answer:
The ECG measures the depolarization and repolarization of the heart muscle. The QRS complex represents the depolarization of the ventricles. The R, R'-L ventricle depolarizes slightly later than the R ventricle.
Step-by-step explanation:
The ECG measures the depolarization and repolarization of the heart muscle and provides information about its functioning. The QRS complex in the ECG represents the depolarization of the ventricles as they pump blood to the lungs and body. The R, R'- L ventricle depolarizing slightly later than the R ventricle, which can be checked in leads V5 or V6.