Question

Typical amplitude of ECG signal is

• A. 5 - 10 mV
• B. 0.5 - 5 mV
• C. 10 - 50 mV
• D. 50 - 100 mV

Hint:

Standard diagnostic surface ECG signals have a very low amplitude, typically between 0.5 mV and 5 mV, requiring low-noise instrumentation amplifiers to safely capture the waveform.

Answer 1

The Correct Option is B

Concept: Biopotentials generated by the human body vary significantly in amplitude and frequency depending on the source organ. Electrocardiogram (ECG) signals measure the electrical activity of the heart using skin electrodes placed on the chest or limbs.

Step 1: Evaluating physiological signal scales.
The depolarization and repolarization waves of the myocardium must pass through internal thoracic tissues, fluids, bone, and skin before reaching surface electrodes. This attenuation reduces the signal amplitude measured at the skin surface:
• A typical surface ECG signal has a peak-to-peak amplitude (dominated by the R-wave) ranging from 0.5 mV to 5 mV (most commonly centered around 1 mV to 2 mV).

Step 2: Eliminating incorrect choices.

• Voltages above $5\text{ mV}$ (such as 10 mV, 50 mV, or 100 mV found in Options A, C, and D) are much larger than typical surface ECG signals. These higher ranges are more characteristic of direct electromyography (EMG) needle insertions or internal cardiac electrograms, validating Option (B) for standard surface recordings.