This quantity’s thermally-activated “creep” is modeled in Anderson–Kim theory. A “pinched” hysteresis loop is a signature of a device whose strength is the derivative of this quantity with respect to charge. The material derivative of this quantity vanishes for infinitely conducting fluids by Alfvén’s theorem. (10[1]-5[1])The voltage produced in the AC Josephson effect (10[1])is equal to the frequency times the quantum (10[1])of this quantity, (10[1])which (10[1])equals h over 2e. (10[1]-5[1])The (10[1])“pinning” (10[1])of this quantity in superconductors (10[2])creates a force (-5[1])that allows them (10[1])to levitate (10[1])magnets. This quantity (-5[1])can be computed as the double integral of “B dot dA.” (10[2])The (10[1])EMF (-5[1])induced in a loop (10[1])is proportional to the time-derivative (10[1])of this quantity, (10[1]-5[1])symbolized (10[1])phi, (10[1])by Faraday’s law. (10[2]-5[1])For 10 points, (10[1])name this quantity that measures the density of magnetic (10[1])field lines passing through a surface. (10[1])■END■ (10[6]0[9])