The general equation for it features a quantity equal to the product of the permittivity constant, permeability constant, and the time derivative of the E-field, which vanishes in the absence of time- varying E-fields. That quantity was introduced in On Physical Lines of Force by James Maxwell, and is called the displacement current. For 10 points, identify this law which states that the magnetic field in a closed loop produced by a current is proportion to the current enclosed in the loop, and 
The general equation for it features a quantity equal to the product of the permittivity constant, permeability constant, and the time derivative of the E-field, which vanishes in the absence of time- varying E-fields. That quantity was introduced in On Physical Lines of Force by James Maxwell, and is called the displacement current. For 10 points, identify this law which states that the magnetic field in a closed loop produced by a current is proportion to the current enclosed in the loop, and is named for a French scientist.
The general equation for it features a quantity equal to the product of the permittivity constant, permeability constant, and the time derivative of the E-field, which vanishes in the absence of time- varying E-fields.
Ampere's Law