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MIT Physics 8.02 - Electricity & Magnetism

SECTION : Electrostatics      

SUBJECT: Repulsion of Charges with Opposite Sign  

Two charges hang from pendulums whose supports can be moved closer or further apart by an external agent. The charges have the same sign, and therefore repel. An external agent tries to move the supports (from which the two positive charges are suspended) together. The force of gravity is pulling the charges down, and the force of electrostatic repulsion is pushing them apart on the radial line joining them. The behavior of the electric fields in this situation is an example of an electrostatic pressure transmitted perpendicular to the field. That pressure tries to keep the two charges apart in this situation, as the external agent controlling the pendulum supports tries to move them together.





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