Final answer:
The normal PR interval for adults is usually between 120 to 200 milliseconds on an ECG. Abnormal PR intervals can suggest various cardiac conditions such as atrioventricular block or bundle branch block.
Step-by-step explanation:
The normal PR interval for adults is usually between 120 to 200 milliseconds on an electrocardiogram (ECG). The PR interval measures the time it takes for an electrical impulse to travel from the atria to the ventricles of the heart.
The PR interval is an important indicator of the proper conduction of electrical signals in the heart. Abnormal PR intervals can suggest various cardiac conditions such as atrioventricular block or bundle branch block.
In conclusion, the normal PR interval for most adults ranges from 120 to 200 milliseconds on an ECG.