Question | Answer |
Frequency | The number of waves passing a point each second. |
Hertz (Hz) | The unit for frequency 1 hertz is 1 wave per second. |
Longitudinal | E.g. sound waves where the direction of energy transfer is parallel with the direction of movement of the energy. |
Medium | Something through which waves travel. |
Pitch | Whether a sound is low or high. |
Infrasound | Sound waves with a frequency below 20Hz which is too low for the human ear to detect. |
Ultrasound | Sound waves with a frequency above 20000Hz which is too high for the human ear to detect. |
Reflect | When a wave bounces off a boundary between two materials. |
Sonar | A way of finding the distance to an underwater object (such as the sea floor) by timing how long it takes for a pulse of ultrasound to be reflected. |
Ultrasounds scan | A way of making an image of part of the body (usually a foetus) using ultrasound waves reflected from parts of the inside of the body. |
Earthquake | A sudden movement within the Earth releasing a large amount of stored energy. |
Seismic waves | Waves produced by an explosion or earthquake and which travels through the Earth. They include P-waves and S-waves. |
Seismometer | An instrument that detects seismic waves. |
Focus | The place where an earthquake begins usually under the surface. |
Epicenter | The point on the surface of the Earth directly above the focus of an earthquake. |
P waves | Longitudinal seismic waves that travel through the Earth. |
S waves | Transverse seismic waves that travel through the Earth. |
Crust | The outer surface of the Earth. |
Mantle | The part of the Earth between the crust and the core. |
Core | The middle of the Earth. |
Refraction | The chang of speed and direction of a wave when it enters a new material. |
Plates | Sections of the outermost layer of the Earth that can move relative to each other. |
Tectonic plates | Pieces of the surface of the Earth which can move around very slowly. |
Convection currents | A current caused by parts of a fluid being at a different temperature and so a different density to the rest of the fluid. |
Tsunami | A huge wave caused by an earthquake or landslide on the sea bed. |