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Diagnostic ultrasound of frequency 3.45 MHz is used to examine tumors in soft tissue. (a) What is the wavelength in air of such
Question
Diagnostic ultrasound of frequency 3.45 MHz is used to examine tumors in soft tissue.
(a) What is the wavelength in air of such a sound wave?
(b) If the speed of sound in tissue is 1500 m/s, what is the wavelength of this wave in tissue? (Take the speed of sound in air to be 343 m/s.)
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2021-07-20T06:34:38+00:00
2021-07-20T06:34:38+00:00 1 Answers
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Answers ( )
Answer:
4.35×10⁻⁴ m
Explanation:
(a)
From wave,
v = λf…………………. Equation 1
Where v = speed of sound in air, λ = wavelength of sound, f = frequency of sound.
Make λ the subject of formula in equation 1
λ = v/f…………….. Equation 2
Given: v = 343, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 2
λ = 343/(3.45×10⁶)
λ = 99.42×10⁻⁶ m
λ = 9.942×10⁻⁵ m
(b)
using,
v’ = λ’f…………… Equation 3
Where v’ = speed of sound in tissue, λ’ = wavelength of sound in tissue.
make λ’ the subject of the equation
λ’ = v’/f………………….Equation 4
Given: v’ = 1500 m/s, f = 3.45 MHz = 3.45×10⁶ Hz
Substitute into equation 4
λ’ = 1500/(3.45×10⁶)
λ’ = 434.783×10⁻⁶
λ’ ≈ 4.35×10⁻⁴ m.