Q.___________ wave in ECG represent atrial depolarization.

An electrocardiogram (ECG) is a graphical recording of the small electrical signals detectable at the body surface as the contraction wave spreads through the heart wall, captured via limb electrodes (two on each arm, two on each leg) and six chest electrodes, using an ECG machine (electrocardiograph) that detects and amplifies the signal. A normal trace shows three waves per cycle: the P-wave (small, upward — atrial depolarisation, the trigger for atrial contraction), the QRS complex (a brief dip, a sharp tall spike, another dip — ventricular depolarisation, the trigger for ventricular contraction, large because of the ventricles' greater muscle mass), and the T-wave (small, broad, upward — ventricular repolarisation, the v …