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Updated: Jul 11, 2026
06:04
Simulation of the Planetary Interior Differentiation Processes in the Laboratory
Published on: November 15, 2013
Seismic Waves within Earth's Outer Core: Multiple Reflection
Science (New York, N.Y.)
|July 19, 1968
Abstract:
Seismic waves reflected as many as four times within Earth's outer core are routinely recorded from large earthquakes. Observations of these waves are confined to rays near grazing incidence on the core-mantle boundary, in agreement with theoretical expectation. Minor adjustments to outer-core velocities may be necessary to account for certain of these arrivals that are not predicted by present core models. A change of 10 kilometers or more in the currently accepted core radius, 3473 kilometers, is not corroborated by the new data.
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01:07Reflection of Waves
When a wave travels from one medium to another, it gets reflected at the boundary of the second medium. A common example of this is when a person yells at a distance from a cliff and hears the echo of their voice. The sound waves (longitudinal waves) traveling in the air are reflected from the bounding cliff. Similarly, flipping one end of a string whose other end is tied to a wall causes a pulse (transverse wave) to travel through the string, which gets reflected upon reaching the wall. In...
01:06Echo
The human ear cannot distinguish between two sources of sound if they happen to reach within a specific time interval, typically 0.1 seconds apart. More than this, and they are perceived as separate sources.
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...
Imagine the sound is reflected back to the ears. Assuming that the source is very close to the human, the difference between hearing the two sounds—the emitted sound and the reflected sound—may be more than the minimum time for perceiving distinct sounds. If this is the case, then the...
01:04Travelling Waves
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01:07Propagation of Waves
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01:16Shock Waves
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01:07Interference and Superposition of Waves
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