# Edexcel Physics 1 Topic 4

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1. What name is given to sound with a frequency greater than 20 000 Hz?
Ultrasound
2. Name three uses of ultrasound
• Sonar - detecting objects under water
• communication between animals
• scanning unborn babies
3. What name is given to sound with a frequency less than 20 Hz?
Infrasound
4. Name three uses of infrasound
• communication between animals
• detecting animal movement in remote locations
• detecting volcanic eruptions and meteors
5. What do we call waves that travel through the ground?
Seismic
6. Name two things that can cause seismic waves
• explosions
• earthquakes
7. Are seismic waves longitudinal or transverse?
• They can be either.
• Longitudinal waves are also known as P waves.
• Transverse waves are also known as S-waves
8. Which boundaries within the Earth reflect or refract seismic waves?
• between the crust and mantle
• between the mantle and the core
9. What do we call the moving plates in the Earths crust?
Tectonic plates
10. What causes tectonic plates to move?
• Convection currents in the Earths mantle
11. What is the cause of Earthquakes?
• Tectonic plates sliding past each other and getting caught.
• When sufficient pressure builds up, they are released causing an earthquake.
12. What do we call the number of complete waves that pass a point in a second?
The wave frequency
13. Name three uses of sonar (using ultrasound)
• mapping the sea floor
• detecting submarines
• detecting shoals of fish
14. What is the epicentre of an Earthquake?
• The point on the Earths surface directly above the focus of the earthquake
15. What are seismometers used for?
To measure the amount that the ground shakes
16. What is a tsunami?
• A huge wave in the sea caused by an earthquake under the sea
17. What is the unit of frequency?
Hertz (Hz)
18. Which waves travel the fastest, P or S?
P (seismic longitudinal) waves travel faster than S waves
 Author: HLHSscience ID: 199158 Card Set: Edexcel Physics 1 Topic 4 Updated: 2014-03-23 10:10:36 Tags: Edexcel Physics1 Topic4 Folders: Description: Edexcel Physics 1 Topic 4 Show Answers: