# Test charge velocity in Coulomb's Law

akhila_k
The force on a test charge Q due to source charge q, depends on both their velocities in addition to several other quantities. For electrostatics, the source charge is at rest (its velocity is zero) but the test charge may be moving. Then how does Coulomb's Law accommodate for this velocity of the test charge?

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The force on a test charge Q due to source charge q, depends on both their velocities in addition to several other quantities. For electrostatics, the source charge is at rest (its velocity is zero) but the test charge may be moving. Then how does Coulomb's Law accommodate for this velocity of the test charge?

The source charge is not just at rest, but fixed. This leads to a static (i.e. constant in time) electric field and no magnetic field associated with the source charge. The test charge is then subject to an electrostatic force only, given by Coulomb's law. This force will change over time as the test charge moves.

akhila_k
If the force is time varying, why doesn't time parameter appear in Coulomb's law? Or Coulomb's law give the force at what time point in test charge's motion?