ECG Electrocardiogram Knowledge Answers and Questions 2

Question 1

Which lead is considered the ground (reference) electrode in a standard 12-lead ECG?

Accepted Answer

Right leg (RL)

Answer

The right leg electrode serves as the ground and does not contribute to any waveform.

Question 2

At standard calibration, one small (1 mm) box on the horizontal axis represents how much time?

Accepted Answer

0.04 seconds

Answer

Each small box equals 0.04 seconds when paper runs at 25 mm/sec.

Question 3

The P wave on an ECG represents which electrical event?

Accepted Answer

Atrial depolarization

Answer

The P wave reflects depolarization spreading across the atria.

Question 4

Where should the V1 chest electrode be placed?

Accepted Answer

4th intercostal space, right sternal border

Answer

V1 is positioned in the 4th intercostal space just right of the sternum.

Question 5

A standard ECG is normally calibrated so that 10 mm of vertical deflection equals what voltage?

Accepted Answer

1 millivolt

Answer

Standard calibration sets 10 mm vertical equal to 1 mV.

ECG (Electrocardiogram) Practice Test