Direct current (DC) is the flow of electric charge in only one direction. ... Alternating current (AC) is the flow of electric charge that periodically reverses direction. If the source varies periodically, particularly sinusoidally, the circuit is known as an alternating current circuit.
The field is
<em><u>E</u></em> = 1 / (4 pi ε₀) Q / <em><u>R</u></em>² directed radially outward from
the center of the shell.
R is the radius of the spherical shell.
Notice that the field is exactly the same as the field due to a point-charge
with magnitude 'Q' that's located at the center of the sphere.
Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field.
Electromagnetic induction has found many applications in technology, including electrical components such as inductors and transformers, and devices such as electric motors and generators.
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday's law of induction. Lenz's law describes the direction of the induced field. Faraday's law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell's equations in James Clerk Maxwell's theory of electromagnetism.