SWITCH that is different from the other silicon-controlled rectifiers in the sense that it can conduct in both directions that is whether the applied gate signal is positive or negative, it will conduct. Thus, this device can be used for AC systems as a switch.It FINDS applications in switching, PHASE control, chopper designs, brilliance control in lamps, speed control in fans, MOTORS, etc. Explanation:TRIAC is used in domestic fan speed control circuits.In the TRIAC-based electronic fan REGULATOR circuit, the main components used are a resistor, capacitor, DIAC, and TRIAC.TRIAC is directly used to control the speed by holding and releasing the current flow. TRIAC:The TRIAC is a 3-terminal semiconductor device and may be considered equivalent to two SCRs connected in antiparallel.TRIAC are bidirectional devices. It is ideal for operation utilizing AC power for switching purposes (operated at power frequency) It can control current flow for both halves in an alternating current cycle.Triac Used in ac voltage regulators, Cycloconverters, inverter The V-I characteristics are shown below.Applications:Lighting control - especially domestic dimmers.Control of fans and small motors.Electronic switches for general AC switching and control TRIAC (Triode for AC) is a semiconductor device widely used in power control and switching applications.It finds applications in switching, phase control, chopper designs, brilliance control in lamps, speed control of motors, etc.