Ultrasound pulses of with a frequency of 1.000 MHz are transmitted into water, where the speed of sound is 1500m/s . The spatial length of each pulse is 12 mm.
a) How many complete cycles are in each pulse?
b) What is the lower bound of the range of frequencies must be superimposed to create each pulse?
c)What is the upper bound of the range of frequencies must be superimposed to create each pulse?
The Attempt at a Solution
a) Δt= 12mm/1500 = 8 * 10^-6
T = 1/f
T = 1/10^6 = 10^-6
So... (8 * 10^-6)/(10^-6) = 8 full cycles in each pulse
b) and c) I have no idea... All I have is..
Δf = 1/Δt = 125,000 Hz.. How do I find the upper/lower bound?