One can determine the heart beat rate by counting the number of …………… in an ECG.

Explanation

To determine the heart rate using an ECG (electrocardiogram), follow these steps:

1. **Understand the Components of an ECG**: An ECG graph consists of several waves, primarily the P wave, QRS complex, and T wave. Each of these waves represents different electrical activities of the heart.

2. **Identify the QRS Complex**: The QRS complex is crucial as it represents the depolarization of the ventricles, which corresponds to the contraction of the heart's ventricles.

3. **Count the QRS Complexes**: To determine the heart rate, count the number of QRS complexes over a specific time period.

...