Physics Glossary – E

East-West Effect

The amount of cosmic rays coming from the west is greater than the amount coming from the east. This is due to the fact that the cosmic rays are mainly positive therefore, the positive rays are deflected by the Earth’s magnetic field. Discovered by Luis Walter Alvarez.


Is when an object moves into the shadow of another. 

Lunar Eclipse

Where the shadow of the Earth falls on the moon.

Solar Eclipse

Happens when the shadow of the moon falls on the Earth.

Elastic Limit

Maximum stress that a material can withstand before it is permanently deformed – once the stress is removed the material will return to its original shape.

Electron Microscope

Is a scientific instrument that uses a beam of highly energetic electrons to examine objects on a very fine scale. There are two different types Transmission Electron Microscope and Scanning Electron Microscope.


A device used to detect electric charge. One version is a gold leaf electroscope in which two leaves of gold are attached to a metal plate, when a charge is placed on the metal plate the leaves will part because like charges repel each other.


A circle whose centre rotates about the the edge of another larger circle. Used by Ptolemy to examine the motion of the planets.

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