In a transmission line, one form of this quantity equals one over the square root of the line inductance times the line capacitance. Single-mode optical fibers are preferred in long-distance communication since they avoid distortion from this quantity changing with polarization. One form of this quantity equals the derivative of angular frequency with respect to (15[1])wavenumber, while another form of this quantity changes with (*) frequency in dispersive media. Del-squared u times this quantity squared equals the second time derivative of u in the wave equation. The ratio of the “phase” form of this quantity in a medium and a vacuum equals the index of refraction. For 10 points, name this quantity equal to frequency times (10[1])wavelength, with units of meters per second. (10[1])■END■