text: Under gauge freedom, the time derivative of a scalar function is subtracted from this quantity to maintaininvariance.
full_question: Under gauge freedom, the time derivative of a scalar function is subtracted from this quantity to maintaininvariance. In the Lorentz gauge condition, the time derivative of this quantity is divided by the speed of lightsquared. The relativistic case in Jefimenko's equations uses the retarded form of this quantity, derived from aspace integral over the charge density. This scalar, and a vector symbolized A, make up a four-vector whosederivative is the electromagnetic tensor. For conservative fields, the Laplacian of this quantity equals negativecharge density over vacuum permittivity in Gauss's Law, since the negative gradient of this quantity equals theelectric field. It equals Coulomb's constant times the sum of all point charges over their distances. For 10points, name this quantity measured in volts.
first_sentence: Under gauge freedom, the time derivative of a scalar function is subtracted from this quantity to maintaininvariance.
raw_answer: electric potential [or phi; or voltage; or V; do not accept "electric potential difference"]