2- Ultrasound waves are harmful for humans. A. True B. False 3- If the frequency of an US wave is doubled, the period is Doubles A. True B. False 4- When the diagnostic ultrasound beam is incident on the surface separating different tissues e reflection can occur when the beam is at right angles to the interface. A. True B. False 5- Specific acoustic impedance as applied to diagnostic ultrasound increases with increasing frequency. A. True B. False 6- Ultrasonic pulses are poorly transmitted by liquids. A. True B. False 7- An ultrasound beam passing through the body produces heating of tissues A. True B. False

2- Ultrasound waves are harmful for humans. A. True B. False 3- If the frequency of an US wave is doubled, the period is Doubles A. True B. False 4- When the diagnostic ultrasound beam is incident on the surface separating different tissues e reflection can occur when the beam is at right angles to the interface. A. True B. False 5- Specific acoustic impedance as applied to diagnostic ultrasound increases with increasing frequency. A. True B. False 6- Ultrasonic pulses are poorly transmitted by liquids. A. True B. False 7- An ultrasound beam passing through the body produces heating of tissues A. True B. False

College Physics

1st Edition

ISBN:9781938168000

Author:Paul Peter Urone, Roger Hinrichs

Publisher:Paul Peter Urone, Roger Hinrichs

Chapter17: Physics Of Hearing

Section: Chapter Questions

Problem 27PE: (a) Ear trumpets were never very common, but they did aid people with hearing losses by gathering...

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What frequency sound has a 0.10m wavelength when the speed of sound is 340 m/s?
(a) Ear trumpets were never very common, but they did aid people with hearing losses by gathering sound over a large area and concentrating it on the smaller area of the eardrum. What decibel increase does an ear trumpet produce it its sound gathering area is 900 cm2 and the area of the eardrum is 0.500 cm2, but the trumpet only has an eficiency of 5.00% in transmitting the sound to the eardrum? (b) Comment on the usefulness of the decibel increase found in part (a).
A tuning fork generates sound waves with a frequency of 246 Hz. The waves travel in opposite directions along a hallway, are reflected by end walls, and return. The hallway is 47.0 m long and the tuning fork is located 14.0 m from one end. What is the phase difference between the reflected waves when they meet at the tuning fork? The speed of sound in air is 343 m/s.
A community is concerned about a plan to bring train service to their downtown from the town's outskirts. The current sound intensity level, even though the rail yard is blocks away, is 70 dB downtown. The mayor assures the public that there will be a difference of only 30 dB in sound in the downtown area. Should the townspeople be concerned? Why?
A sound wave propagates in air at 27C with frequency 4.00 kHz. It passes through a region where the temperature gradually changes and then moves through air at 0C. Give numerical answers to the following questions to the extent possible and state your reasoning about what happens to the wave physically. (a) What happens to the speed of the wave? (b) What happens to its frequency? (c) What happens to its wavelength?
(a) How far apart are two layers of tissue that produce echoes having round-trip times (used t0 measure distances) that differ by 0.750s ? (b) What minimum frequency must the ultrasound have to see detail this Small?
An interstate highway has been built through a neighborhood in a city. In the afternoon, the sound level in an apartment in the neighborhood is 80.0 dB as 100 cars pass outside the window every minute. Late at night, the traffic flow is only five cars per minute. What is the average late-night sound level?
A train sounds its horn as it approaches an intersection. The horn can just be heard at a level of 50. dB by an observer 10 km away. (a) What is the average power generated by the horn? (b) What intensity level of the horns sound is observed by someone waiting at an intersection 50. m from the train? Treat the horn as a point source and neglect any absorption of sound by the air.
An interstate highway has been built through a neighborhood in a city. In the afternoon, the sound level in an apartment in the neighborhood is 80.0 dB as 100 cars pass outside the window every minute. Late at night, the traffic flow is only five cars per minute. What is the average late-night sound level?
How can an object move with respect to an observer so that the sound from it is not shifted in frequency?
A cowboy stands on horizontal ground between two parallel, vertical clifTs. He is not midway between the cliffs. Me fires a shot and hears its echoes. The second echo arrives 1.92 s after the first and 1.47 s before the third. Consider only the sound traveling parallel to the ground and reflecting from the cliffs, (a) What is the distance between the cliffs? (b) What If? If he can hear a fourth echo, how long after the third echo does it arrive?
The toadfish makes use of resonance in a closed tube to produce very loud sounds. The tube is its swim bladder, used as an amplifier. The sound level of this creature has been measured as high as 100. dB. (a) Calculate the intensity of the sound wave emitted. (b) What is the intensity level if three of these toadfish try to make a sound at the same time?