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Sound Waves — Physics STD 11 Science — Question

Gujarat BoardEnglish MediumSTD 11 SciencePhysicsSound Waves2 Marks
Question
Ultrasonic waves of frequency 4.5MHz are used to detect tumour in soft tissues. The speed of sound in tissue is 1.5km/s and that in air is 340m/s. Find the wavelength of this ultrasonic wave in air and in tissue.
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Answer

Given $\text{V}_\text{air}=340\text{m/s},\ \text{n}=4.5\times10^6\text{Hz}$$\Rightarrow\lambda_\text{air}=\Big(\frac{340}{4.5}\Big)\times10^{-6}=7.36\times10^{-5}\text{m}$
$\text{V}_\text{tissue}=1500\text{m/s}$
$\Rightarrow\lambda_\text{t}=\Big(\frac{1500}{4.5}\Big)\times10^{-6}$
$=3.3\times10^{-4}\text{m}.$

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