Question

(a) Find the size of the smallest detail observable in human tissue with 20.0-MHz ultrasound. (b) Is its effective penetration depth great enough to examine the entire eye (about 3.00 cm is needed)? (c) What is the wavelength of such ultrasound in 0ºC air?

Answer 1

Answer:

(a) λ=77×10⁻⁶m

(b)Yes its enough to examine entire eye,

(c)λ=16.65μm.

Explanation:

The ultrasonic sound are used to detect problems in human body by using device consisting of transmitter and detector .

The speed of sound in human tissue is 1540m/s.

The wavelength of sound is 20MHz.

(a) let the velocity of sound in human tissue is v = 1540m/s.

                v=fλ

           λ= $\frac{v}{f}$ =$\frac{1540}{20MHz}$ = 77×10⁻⁶m

             λ=77×10⁻⁶m

(b)  we can scan effectively upto the depth of  about 500λ

                   500λ=500× (77×10⁻⁶)= 3.85cm

            Yes its enough to examine entire eye,

(c) In air the  velocity of sound is 331m/s.

              λ=$\frac{v}{f}$  = $\frac{331 m/s}{20Mhz}$  = 16.65μm

            λ=16.65μm.