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INPUT   DATA

♥ EXAMPLE Of Input/Output

Title

Charge on body #1, q1		10-6C
Charge on body #2, q2		10-6C
Distance between bodies, r		m
Dielectric constant of medium, K

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OUTPUT   VARIABLES   &   GRAPHS

Variables	Values	Units
♦  Electrostatic force, FE		N
♦  Electric field at #2 due to #1, E1		N/C
♦  Electric field at #1 due to #2, E2		N/C

Coulomb's Law and Electric Fields

This law is an inverse-square law indicating the magnitude and direction of electrostatic force that one stationary, electrically charged object (ideally, a point source) exerts on another. If the two point charges have the same sign (polarity), they repel each other. If they have opposite signs they attract each other. The scalar version of the law can be represented by the equation:

   F_E = [1/4πε₀K][q₁q₂/r²]

Also, the electric field at a given from a point charge is given as:

   E₁ = [1/4πε₀K][q₁/r²]

where
     F_E = electrostatic force on both bodies
     E = strength of electric at a given distance from charge
     ε₀ = permittivity of free space = 8.85x10^-12C²/N.m²
     K = dielectric constant, (=1 for vacuum, 1.0006 for air, 80 for water, 1200 for barium titanate)
     q_i = charge at body/point i
     r = distance from the charged body or between charged bodies

Tips

    ◊ Use link EXAMPLE Of Input/Output  to demo data entry expectations and results; you may edit & use it as starting point

BIBLIOGRAPHY

• Bueche FJ & Hecht E; College Physics, Schaum's Outlines Series; McGraw Hill, New York, 1997.
• Lowe TL & Rounce JF; Calculations For A-Level Physics; Nelson Thornes Ltd, Cheltenham, UK, 2002