OCR Gateway Additional Science B Higher P4- Ultrasound

What is ultrasound?

Sound above 20000 hz which it higher frequency for humans to hear

How does ultrasound travel?

As a pressure wave containing compressions and rarefactions

What are compressions?

Areas of high pressure so the particles are squashed together

What are rarefactions?

Areas of low pressure so the particles are spread out

How does the density of the medium affect the sound travelled?

Sound is a pressure wave so it only travels through a medium and the denser the medium the faster it travels because more particles in a given volume so so sound passed on faster and is a longitudinal wave

How are the particles in a longitudinal wave different from the particles in a transverse wave?

In a longitudinal wave the vibrations of the particlesare parallel to the direction of the wave which produces a pressure wave. In a transverse wave the particles move at right angles to the direction of the wave

How does an ultrasound scan work?

A pulse of ultrasound is sent into the patients body and at each boundry between tissues some fo the ultrasound is reflected and the rest is transmitted. The returning echoes are recorded and used to build up an image of the internal structure…