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- PHY102 Physics II © Dr.Cem Özdoğan
- The force of repulsion/attraction due to the charge properties of objects is called an electrostatic force.
- Coulomb’s law describes the electrostatic force (or electric force) between two charged particles.
- The magnitude of the electric forces between charged objects is measured by “Torsion Balance” which was invented by Charles Augustin De Coulomb. http://www.dnatube.com/video/11874/Application-Of-Coulombs-Torsion-Balance
- Charles-Augustin
- De Coulomb
- (1736–1806)
- Why static? We study the snapshot of the system.
- If the particles have charges q2 and q1, are separated by distance r, and are at rest (or moving only slowly) relative to each other, then the magnitude of the force acting on each due to the other is given by
- Just calculate magnitude(s) of forces!
- Note that Newton’s Third Law says |F12| = |F21|
- where ε0 = 8.85 ×10-12 C2/N.m2 is the constant for permittivity of free space.
- Response of the medium to the external
- If not air/vacuum: ε0 → ε
- The ratio 1/4πε0 is often replaced with the electrostatic constant (or Coulomb constant) k=8.99×109 N.m2/C2.
- First make analysis of magnitudes of the forces then introduce (unit) vector