Ultrasound Flashcards

All 4 cards in this deck

What is ultrasound?

Sound waves with a frequency higher than the upper limit of human hearing, i.e. above 20 kHz.

What happens to ultrasound when it meets a boundary between two different media?

It is partially reflected, and the time for the reflection to reach a detector shows how far away the boundary is.

What are the steps to find the distance to a boundary from an ultrasound echo time?
e.g. echo returns after 0.004 s at a speed of 1500 m/s

1. Total distance $= v \times t = 1500 \times 0.004 = 6$ m
2. This is there and back, so halve it
3. Distance to the boundary $= 3$ m

True or false? Ultrasound is a type of electromagnetic wave.

False. It is a longitudinal (mechanical) sound wave and needs a medium.