What does a electromagnetic pulse can do to stop a wrist watch from ticking?
An EMP is as it sounds, a pulse of electromagnetic energy, this induces a very high current (thousands of volts) in parts of the watch, and since many electrical items, such as microchips, are very sensitive to high voltages, it causes them to break.
If you're checking your own pulse, you can check either wrist, where you might see the throbbing of the pulse, or either side of your neck, using the minute hand of your watch, for a minute. IF you are checking someone else's pulse, the same principles apply as use above. Just be careful not to use your thumb to check wrist pulses or you might actually be counting your own.