Tag: medical imaging

Among the above, high frequency is property of ultrasound.

Ultrasonic waves are not harmful but just humans cant hear those frequency.

Ultrasonics, vibrations of frequencies greater than the upper limit of the audible range for humans, that is, greater than $20kHz$.

The frequencies used in ultrasonic diagnosis are in the range of 1 to 10 MHz. The speed of sound waves in the tissues of the human body averages about 1540 m/s (close to that for water). So, the wavelength of a 1 MHz wave is about $λ = v/f = 1540/1∙106 = 1.5∙10–3 m = 1.5 mm$.

Ultrasound can be used in 

Infrasound, sometimes referred to as low-frequency sound, is sound that is lower in frequency than 20 Hz or cycles per second, the "normal" limit of human hearing. So 5Hz is infrasonic.

Audible range of frequency for human ear is  $20 \ Hz$ to $20 \ kHz$. Humans cannot hear sounds having frequency other than this range.
Sounds having frequency lower than $20 \ Hz$ are known as infrasonic sounds and that having frequency greater than $20 \ kHz$ are known as ultrasonic sounds. Thus, humans can neither hear infrasonic nor ultrasonic sounds.

Aquatic animals as dolphins also use ultrasound to catch their prey. Statement is true.

The options in the question are given unnecessarily. It can be a direct question.
Below are the applications of ultrasound.

• Ultrasound has been used in a variety of clinical settings, including obstetrics and gynecology, cardiology and cancer detection. The main advantage of ultrasound is that certain structures can be observed without using radiation. Ultrasound can also be done much faster than X-rays or other radiographic techniques. 
• Ultrasound is well known to have a significant effect on the rate of various processes in the food industry. Using ultrasound, full reproducible food processes can now be completed in seconds or minutes with high reproducibility, reducing the processing cost, simplifying manipulation and work-up, giving higher purity of the final product, eliminating post-treatment of waste water and consuming only a fraction of the time and energy normally needed for conventional processes. Several processes such as freezing, cutting, drying, tempering, bleaching, sterilization, and extraction have been applied efficiently in the food industry. The advantages of using ultrasound for food processing, includes: more effective mixing and micro-mixing, faster energy and mass transfer, reduced thermal and concentration gradients, reduced temperature, selective extraction, reduced equipment size, faster response to process extraction control, faster start-up, increased production, and elimination of process steps. Food processes performed under the action of ultrasound are believed to be affected in part by cavitation phenomena and mass transfer enhancement. 
• Ultrasound is used in the synthesis of nanostructured materials.
• Devices limited to low ultrasonic frequencies, have a number of industrial applications, including drying, ultrasonic cleaning, and injection of fuel oil into burners. 

ultrasound is used for removing kidney stones.when ultrasound are targeted on such stone,the stones start vibrating at high frequency.the stone due to this vibratory motion. Breakdown into fine particles.ultrasounds and infrasounds are not audible to man.ultrasound have frequency more than 20kHz.a doorbell can produce an audible sound. Infrasound have frequency below 20Hz, X is ultrasound. Y is infrasound, Z is audible sound.