6B Ch 21

# 9875 x 109 nm2c2 14 is the permittivity free space

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Unformatted text preview: ulomb s Law Fe = ke Q1 Q2 r Magnitude 2 •  The SI unit of charge is the Coulomb, C •  ke is called the Coulomb Constant –  ke = 8.9875 x 109 N.m2/C2 = 1/(4πεο) –  εο is the permittivity free space –  εο = 8.8542 x 10-12 C2 / N.m2 Note the similarity to Newtons law of gravitation! Vector Nature of Electric Forces •  In vector form, Q1 Q2 ˆ F12 = ke 2 r12 r •  ˆ –  r12 is a unit vector directed from q1 to q2 •  The like charges produce a repulsive force between them Comparing Gravitation and Electrostatics Gravitation mass force between masses Grav. acceleration (or field) Electrostatics m m1m2 FG = G 2 r G=F/m charge force between charges Electric field Q Q1Q2 FE = k 2 r E= F Q Force mg Force QE Work mgh Work QEd Potential Energy mgh Potential Energy QEd = QV Vector Nature of Electrical Forces •  The force on q1 is equal in magnitude and opposite in direction to the force on q2 –  F12 = −F21 •  With like signs for the charges, the product Q1Q2 is positive and the force is repulsive •  With opposite signs...
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## This document was uploaded on 02/21/2014 for the course CHEM 110A 110a at UCLA.

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