1) PLCs were first used by the __________ industry in the late 1960s. a) railroad b) defense c) automotive d) steel 2) The PLC recognizes only _____. a) push-buttons b) pressure switches c) open or closed contacts d) float switches 3) The PLC is a special type of _____ designed to perform a special function a) die b) motor c) robotic arm d) computer 4) The most popular way to isolate the CPU from the external circuit is through _____. a) optical isolation b) small relays c) rheostats d) bridge rectifiers 5) The ____ is used to connect the CPU to the load. a) power supply b) input module c) output module d) opto-isolator 6) In the relay method of isolation, the CPU is isolated through the use of a(n) _______. a) LED b) laser c) electrostatic buildup d) magnetic field 7) The actual logic of the control circuit is performed by a) physical relays b) internal relays c) contacts d) RAM 8) A(n) ______ is connected across the AC input to help eliminate any voltage spikes that may occur. a) rheostat b) metal-oxide varistor c) avalanche diode d) gas tube 9) The current rating of most outputs can range from 0.5 to about _____ amperes, depending on the make of the controller and the type of output being used. a) one b) two c) three d) five 10) PLCs are designed to be programmed with  a) ladder diagrams b) BASIC c) higher-order languages d) relays 11) The ______ is the “brains” of the PLC. a) power supply b) CPU c) I/O rack d) program loader 12) The______ is used to program the CPU. a) I/O rack b) power supply c) tape deck d) loading terminal 13) An electronic device that is often used to help overcome the problem of induced noise is the _____. a) float switch b) LED c) MOV d) differential amplifier 14) Highlighting a contact means that there is a _____ through that contact. a) complete circuit b) short circuit c) change of state d) troubleshooting element 15) Electrical noise is such a problem in some installations that several manufacturers are using _______instead of wires for connection to the I/O rack. a) transistors b) coaxial cables c) optical cables d) radio signals

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