Lesson 7: Waves for detection/ exploration Flashcards
1
Q
What is ultrasound?
A
- Ultrasound waves have a higher frequency than the upper limit of hearing for humans.
2
Q
What happens when ultrasound waves hit the boundary between 2 different mediums?
A
- Ultrasound waves are partially reflected when they hit the boundary between 2 different mediums.
3
Q
What can ultrasound be used for?
2 main uses.
A
- Medical and industrial imaging.
- Time taken for wave to reflect from boundary (ie. reach a detector) can determine how far the boundary is
- Industrial - detectinf faults in devices.
4
Q
What do seismic waves include? How are seismic waves produced?
A
- Seismic waves include P waves and S waves.
- Seismic waves are produced by earthquakes.
5
Q
What type of wave is a P wave? How is a P wave different to an S wave (what can it travel through, what’s it’s speed like?)
A
- P waves are longitudinal waves.
- P waves can travel through both solids and liquids.
- P waves travel faster than S waves (quicker through solid than through liquid.)
6
Q
What type of wave is an S wave?
A
- S waves are transverse waves.
- S waves can only travel through solids.
7
Q
How can scientists use P and S waves to show evidence for the structure of the earth?
A
- S waves can only travel through solid (seismometers will detect that the seismic waves don’t go through the centre of the earth - showing centre is liquid.)
- P waves slow down when they enter outer core - this causes them to refract. SHOWS outer core is a liquid.
8
Q
How can echo sounding ultrasound be used in deep water?
A
- High frequency sound wave can be used to detect objects in deep water and measure water depth.
9
Q
Why is ultrasound much safer than X- rays?
A
- Ultrasound is much safer than X- rays because ultrasound doesn’t cause mutations/ increase the risk of cancer.
