[[Image:Qsource13.png|thumb|400px|Defining the capacitance observable in the Field Integral dialog.]]
In the above table, C represents an open curve (path), C<sub>o</sub> represents a closed curve (loop), S represents an open surface like a plane, S<sub>o</sub> represents a closed surface like a box, and V represents a volume. In the case of mutual inductance, S' represents an open surface or plane passing through the second (coupled) inductor, and Φ'<sub>H</sub> represents the magnetic flux linkage due to the magnetic field of the first inductor passing through the second inductor.