GUIDE, PRACTICE QUESTIONS AND
ANSWERS
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Updated 2026 Questions and Answers
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, Normal QSR interval 0.04-0.12 seconds
Normal PR interval 0.12-0.20 seconds
Normal QT interval 0.36-0.44
one small box 0.04 seconds
one large box 0.20 seconds
Six second tracing method Count number of R waves that appear within that 6 second period and multiply it by 10
The 300 method use the number 300 divided by the number of big boxes between R waves
The 1500 method Count number of small squares between two consecutive R-waves and divide that
number by 1500, it is the most accurate method of obtaining the heart rate but can only
be used on regular rhythms.
P wave atrial depolarization (contraction)
QRS wave complex ventricular depolarization
Q wave first negative deflection after P wave
R wave first positive deflection after P wave
S wave first negative deflection after R wave
T wave ventricular repolarization (relaxation)