Negative resistance  From Wikipedia, the free encyclopedia Jump
to: navigation, search Fluorescent lamp, a device with negative
differential resistance.[1][2] In operation, an increase in
current through the fluorescent tube causes a drop in voltage
across it. If the tube were connected directly to the power
line, the falling tube voltage would cause more and more current
to flow, until it destroyed itself.[1][3] To prevent this,
fluorescent tubes are connected to the power line through a
ballast. The ballast adds positive impedance (AC resistance) to
the circuit to counteract the negative resistance of the tube,
limiting the current.[1]  In electronics, negative resistance
(NR) also called negative conductance[4] is a property of some
electrical circuits and devices in which an increase in voltage
across the device's terminals results in a decrease in electric
current through it.[5][6][7] This is in contrast to an ordinary
resistor in which an increase of applied voltage causes a
proportional increase in cur