ECG depicts the depolarisation and repolarisation process during the cardiac cycle. In the ECG of a normal healthy individual one of the following waves is not represented.

Options

A. Depolarisation of atria
B. Repolarisation of atria
C. Depolarisation of ventricles
D. Repolarisation of ventricles

Answer

### Step-by-Step Solution:

1. **Understanding ECG**:
- ECG stands for electrocardiography, which is a method used to record the electrical activity of the heart over a period of time.
- It produces a graph that displays the electrical impulses in the heart.

2. **Components of ECG**:
- The ECG waveform consists of several key components: P wave, QRS complex, and T wave.
- Each of these waves represents different phases of the cardiac cycle.

3. **P Wave**:
- The P wave represents the depolarization of the atrial muscles. This is when the atria contract to push blood into the ventricles.

4. **QRS Complex**:
- The QRS complex is the most prominent part of the ECG and represents the depolarization of the ventricles. This is when the ventricles contract to pump blood to the lungs and the rest of the body.
- It also includes the repolarization of the atria, but this is not visually represented on the ECG.

5. **T Wave**:
- The T wave represents the repolarization of the ventricles. After the ventricles contract, they need to reset their electrical state to prepare for the next heartbeat.

6. **Identifying the Missing Wave**:
- In a normal ECG, the repolarization of the atria is not represented. While the depolarization of the atria (P wave) is shown, the repolarization of the atria occurs during the QRS complex but is not distinctly visible.

7. **Conclusion**:
- Therefore, in the ECG of a normal healthy individual, the wave that is not represented is the repolarization of the atria.