1. Feb 3, 2009

### QueryQueen86

This question is on the operation of a CRT.

In a heart rate monitor, the time base is a standard 0.40s/ms.
The distance between adjacent peaks on the display is 1.25cm per heart beat.
Calculate the time taken for one heart beat.

Any help with this will be very much appreciated. I missed a few lectures due to illness and now I'm so behind. I don't even know where to start with this!!

2. Feb 3, 2009

### LowlyPion

Welcome to PF.

I don't think I exactly understand your problem statement, because typically your oscilloscope will be given as time/div.

Now if you had said .40s/div then that would indicate to me that you have a .5sec peak to peak, for 1 heart beat, or 60/.5 = 120 beats per minute.

3. Feb 3, 2009

### mgb_phys

You have copied this down wrong. The timebase must be time/distance, ie 0.4s/cm

Then if you measure the distance on the screen (1.25cm) and you know how fast the trace is moving you can work out how many seconds the 1.25cm represents.