<prompt> In ECG one small division measures:0.04 sec0.4 sec0.02 sec0.1 sec  <response>: Ans: a 0.04 sec Ref: Ganong, 22nd ed, p. 550In ECG one small duration measures 0.04 sec.ECG:PR interval -- 0.12 - 0.2 secQRS -- 0.08 -0.10 secQT interval -- 0.40 - 0.43 secProlonged PR interval: Hyperkalemia 1st degree heart block abnormally prolonged PR 2nd degree Mobitz type 1 gradual prolongation of PR interval with missing of a beatShort PR interval: Tachycardia WPW syndromeAbsent P waves: Atrial fibrillationDelta waveJ wave Osborn waveSine wave patternInverse tick: WPW syndrome: Hypothermia: Hyperkalaemia: Digoxin 