High‑intensity focused ultrasound (HIFU) is one treatment for certain types of cancer. During the procedure, a narrow beam of high‑intensity ultrasound is focused on the tumor, raising its temperature to nearly 90∘C and killing it. A range of frequencies and intensities can be used, but in one treatment a beam of frequency 3.60 MHz. produced an intensity of 1400.0 W/cm2. The energy was delivered in short pulses for a total time of 2.70 s. over an area measuring 1.20 mm by 5.20 mm. The speed of sound in the soft tissue was 1580 m/s, and the density of that tissue was 1500.0 kg/m3. What was the wavelength ? of the ultrasound beam? How much energy ?total was delivered to the tissue during the 2.70s treatment?

ultrasound physics. What is the power for a transducer if the I (SATA) is 32 mW/cm2 and the scanned area is 3 cm2?

The light intensity (3.431x10^2) cm from a point source is (1.3730x10^0) kW/m². What is the intensity (2.32713x10^2) m away from the same source? Express your result with four significant figures in W/m². Note: Your answer is assumed to be reduced to the highest power possible.

A stationary police car emits a sound of frequency 1200 HzHz that bounces off of a car on the highway and returns with a frequency of 1260 HzHz. The police car is right next to the highway, so the moving car is traveling directly toward or away from it. What frequency would the police car have received if it had been traveling toward the other car at 23.0 m/sm/s ?

1. (a) What is the intensity in w/m of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 540 J of energy into a circular spot 2.2 mm in diameter in 1.5 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. w/m? (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about damaging if they enter your eye. times that of the sun, so clearly lasers can be very

Light is an electromagnetic wave and travels at a speed of 3.00 x 10° m/s. The human eye is most sensitive to yellow-green light, which has a wavelength of 5.68 × 107 m. What is the frequency of this light?

AM radio signals are broadcast at frequencies between 550 kHz (kilohertz) and 1600 kHz and travel at 3 x 10^8 m/s. a) What is the range of wavelengths for those signals? b) FM frequencies range between 88 MHz (megahertz) and 108 MHz and travel at the the same speed. What is the range of the FM frequencies.

1. (a) What is the intensity in W/m² of a laser beam used to burn away cancerous tissue that, when 90.0% absorbed, puts 650 J of energy into a circular spot 1.9 mm in diameter in 4 s? Hint: The laser is a collimated beam of light and does not produce a spherical wave. W/m² (b) Reflect on how this intensity compares to the average intensity of sunlight (about 1W/m²) and the implications that would have if the laser beam entered your eye. Note how your answer depends on the time duration of the exposure. The intensity of a laser is about be very damaging if they enter your eye. ✓times that of the sun, so clearly lasers can

Under favorable conditions, the human eye can detect light waves with intensities as low as 2.50 × 10−12 W/m2. A) At this intensity, what is the average power incident on a pupil of diameter 8.20 mm in W B) If this light is produced by an isotropic source 15.5 m away, what is the average power emitted by the source? in W

An interface is formed between a block of aluminium (with an acoustic impedance of 1.8 x 107 kg m2 s') and a block of copper (with an acoustic impedance of 4.6 x 107 kg m-2 s-1). Longitudinal sound waves travelling through the aluminium are normally incident on the boundary, and are partially reflected. a) What is the ratio of the amplitude of the reflected wave to that of the incident wave? Number b) What is the ratio of the amplitude of the transmitted wave to that of the incident wave? Number c) What percentage of the incident power is transmitted? Number d) What percentage of the incident power is reflected? Number % Ouit P Sove Questi