Question

What's the frequency of 0.19-mm-wavelength ultrasound used in fetal imaging? the waves travel at 1.5 km/s?

Answer 1

The basic relationship between frequency, wavelength and speed of a wave is given by:

`f= (v)/(\lambda)`
where
f is the frequency
v is the wave speed

`\lambda` is the wavelength

The ultrasound wave in our problem has wavelength of

`\lambda = 0.19 mm = 0.19 \cdot 10^(-3)m`
and speed of

`v=1.5 km/s = 1.5 \cdot 10^3 m/s`
So its frequency is

`f= (v)/(\lambda)= (1.5 \cdot 10^3 m/s)/(0.19 \cdot 10^(-3) m)=7.89 \cdot 10^6 Hz`