Q. 27

Expert-verified
Found in: Page 1138

### Physics for Scientists and Engineers: A Strategic Approach with Modern Physics

Book edition 4th
Author(s) Randall D. Knight
Pages 1240 pages
ISBN 9780133942651

# Ultrasound pulses with a frequency of 1.000 MHz are transmitted into water, where the speed of sound is 1500 m /s. The spatial length of each pulse is 12 mm.a. How many complete cycles are contained in one pulse?b. What range of frequencies must be superimposed to create each pulse?

.a) Number of cycle complete in one pulse is 8

.b) Range of frequencies 0.938 MHz f 1.063 MHz

See the step by step solution

## Step 1 Given Information Frequency of Ultrasound pulse 1.000 MHz, Speed of sound is  1500 m/s and length of each pulse is 12 mm

.a) The number of complete cycles in one pulse can be obtained by dividing the spatial length of the pulse by the wavelength of the ultrasound pulse, where the wavelength can be calculated as follows

Number of cycle complete in one pulse

## b) The ultrasound pulse is a wave packet that satisfies the equation

first, we need to find the pulse duration , and that can be done by finding the period of the wave and multiply it by the number of complete cycles in one pulse. The period is

thus, the duration of the pulse (the wave packet ) is

now can be calculated as

Finally, the range of frequencies that must be superimposed to create the given pulse is