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Electricity and the Atom Archived 2009-02-21 at the Wayback Machine—a chapter from an online textbook; A maze game for teaching Coulomb's law—a game created by the Molecular Workbench software; Electric Charges, Polarization, Electric Force, Coulomb's Law Walter Lewin, 8.02 Electricity and Magnetism, Spring 2002: Lecture 1 (video). MIT ...
If the resistance is not constant, the previous equation cannot be called Ohm's law, but it can still be used as a definition of static/DC resistance. [4] Ohm's law is an empirical relation which accurately describes the conductivity of the vast majority of electrically conductive materials over many orders of magnitude of current.
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge . The word "static" is used to differentiate it from current electricity , where an electric charge flows through an electrical conductor .
However, since the magnetic field is described as a function of electric field, the equations of both fields are coupled and together form Maxwell's equations that describe both fields as a function of charges and currents. Evidence of an electric field: styrofoam peanuts clinging to a cat's fur due to static electricity.
Introducing the constant of proportionality, the resistance, [14] one arrives at the usual mathematical equation that describes this relationship: [15] =, where I is the current through the conductor in units of amperes , V is the potential difference measured across the conductor in units of volts , and R is the resistance of the conductor in ...
where r is the distance between the point charges q and Q, and q and Q are the charges (not the absolute values of the charges—i.e., an electron would have a negative value of charge when placed in the formula). The following outline of proof states the derivation from the definition of electric potential energy and Coulomb's law to this formula.
In physics (specifically electromagnetism), Gauss's law, also known as Gauss's flux theorem (or sometimes Gauss's theorem), is one of Maxwell's equations. It is an application of the divergence theorem , and it relates the distribution of electric charge to the resulting electric field .
This equation, along with the continuity equation for J and the Poisson's equation for E, form a set of partial differential equations. In special cases, an exact or approximate solution to these equations can be worked out by hand, but for very accurate answers in complex cases, computer methods like finite element analysis may be required.