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What an ECG machine measures

What an ECG machine measures

Torso with ECG electrodes feeding a high-input-impedance differential amplifier that cancels common mains noise and outputs an amplified trace

An electrocardiogram, or ECG, records the tiny voltage changes produced when waves of electrical activity called depolarisation and repolarisation spread through the heart. By the time the signal reaches the skin it is only about 111 to 2 mV2^{~}\text{mV}2 mV, so a simple ECG machine must detect a very weak signal.

Simple ECG machines and the normal ECG waveform (A-level only) Lesson

  1. A Level
  2. /Physics
  3. /Simple ECG machines and the normal ECG waveform (A-level only)

Step-by-step lessons on AQA A Level Physics Simple ECG machines and the normal ECG waveform (A-level only). Each one builds up to exam-style questions. Physics is one of the most mathematically demanding A Levels -- at least 40% of the marks require maths skills at Level 2 (GCSE) standard or above, so build calculation and graph-handling fluency alongside the conceptual content from the start.

Lessons