If the epoch/timebase is set for 20 seconds/screen, what does each subdivision equal if the screen is divided into 10 subdivisions?

When the epoch/timebase is set for 20 seconds per screen, the total duration of the screen's display is determined to be 20 seconds. If this display is divided into 10 equal subdivisions, each subdivision represents a fraction of that total time.

To find the duration of each subdivision, you would take the total time (20 seconds) and divide it by the number of subdivisions (10).

So, the calculation is:

20 seconds ÷ 10 subdivisions = 2 seconds per subdivision.

Therefore, each subdivision on the screen equals 2 seconds, making that the correct answer. This calculation is fundamental in understanding how time is represented in EEGs, as it helps in analyzing the EEG waveform over specified intervals.