91影视

Frequency emitted is $2.00\text{鈥塎贬锄}$

Sound鈥檚 speed is$1500\text{鈥尘}/\text{s}$

Number of beats per second are $72$

The frequency of the sound wave is defined as the number of oscillation produced per unit time. It is given as-

$\mathbf{f}\mathbf{=}\frac{v}{位}$

where, v is the velocity ,$\mathit{位}$ is the wavelength androle="math" localid="1655818635098" $\mathit{f}$ is the frequency of sound wave.

The frequency of the ultrasound waves is by using equation $f=2.40脳{10}^6\text{鈥塇锄}$.The wavelength of the wave is $位=\frac{v}{f}$

Range of the frequencies is$f_1=1.00\text{鈥塎贬锄}$ to$f_2=20\text{鈥塎贬锄}$ . The corresponding wavelengthrole="math" localid="1655818948502" $f_2$ to is smaller than the corresponding wavelength to$f_1$ , according the equationrole="math" localid="1655819020395" $\mathrm{v}=\mathrm{位蹿}$ as v does not change in the same medium. So,

${位}_2=\frac{1.5脳{10}^3\text{鈥尘/s}}{\begin{array}{c}20.0脳{10}^6\text{鈥塇锄}\\ =0.075脳{10}^{鈭�3}\text{鈥尘}\\ =0.075\text{鈥尘m}\end{array}}$

${位}_1=\frac{1.5脳{10}^3\text{鈥�}m/s}{\begin{array}{c}1.00脳{10}^6\text{鈥�}Hz\\ =1.5脳{10}^{鈭�3}\text{鈥�}m\\ =1.5\text{鈥�}mm\end{array}}$

Therefore, the corresponding wavelengths are$0.75mm$ to $1.5mm$.