The space between two fine black lines (or one square) corresponds to what amount of time?

The space between two fine black lines (or one square) corresponds to what amount of time?

• A. 0.06 seconds
• B. 0.04 seconds
• C. 0.03 seconds
• D. 0.05 seconds

Answer: (B)

In standard EKG paper, each small square represents a specific duration of time. The standard dimensions of the EKG paper are such that each small square, often referred to as one fine black line or square, measures 1 mm x 1 mm. The time duration represented by a small square is 0.04 seconds.

This is derived from the fact that the paper is usually moving at a speed of 25 mm per second during the recording of the EKG. Since there are 5 small squares in one large square, and a large square represents 0.2 seconds (as 0.2 seconds divided by 5 squares equals 0.04 seconds per small square), this reinforces the correct identification of time represented by the space between two fine black lines. Understanding this concept is essential for accurately interpreting the timing of heartbeats and intervals on the EKG.