If impulses are travelling at 50Hz. How many milliseconds apart are 2 impulses?

50Hz = 50 impulses per second so the interval between 2 is 1/50 = 0.02s; or [u]20mS.[/u]

Note: this question says "impulses", not waves.

0.02 second.

Mmmm is 50Hz = 0.02s (1/50) ? Which would be 20 milliseconds. But yeah, no, no idea don't listen to me