ENTC 410 exam 3 question n answers 2023

ENTC 410 exam 3 Potentiometer if position senesors - correct answer Linear position and angular position Potentiometer resolution - correct answer %resolution = (100/N)% Capacitive position and proximity sensors - correct answer C=0.225kA/D^2 (k is relative dielectric constant, A is effective surface area, d is distance between the plates) Capacitor consists of - correct answer two plates separated by and insulating matl Proximity sensor - correct answer Responds to near presence of an object (capacitors can be used to send conductive and non conductive objects) Inductive proximity sensors - correct answer Simply a coil wire wrapped around a core (L=((rN)^2/(9r+10l)u.v.r) [r is radius of core; N is numb of coils; l is effective length of core in inches; u.v.r is relative permeability of core) Inductive proximity sensors are - correct answer PNP and NPN a power supply is needed for the coil to generate mag force as a core moves in and out of the coil. NPN - correct answer Sinking and load is connected on top with (+) or before the switch PNP - correct answer Sourcing and load is connected on bottom with (-) or after the switch PNP and NPN - correct answer Consume a small amount of current to operate the internal circuitry Solid state relay - correct answer Does not have moving parts/ more realizable / there is a polarity different (direction) / communicates through light Optical sensors - correct answer Perform two functions : detecting presence of light/measures intensity of light Common optical sensing devices - correct answer Photo-conductive devices; photo-voltaic; phototransistors; integrated optical sensing devices Photo conductive devices - correct answer Operate depending on the amount of light striking the device, use light-sensitive resistors whose resistance changes in response to changes in light intensity, also called photo-resistive cell or LDR LDR - correct answer Light resistant devices Photo-voltaic devices - correct answer Converts light energy into electrical energy, when exposed to light it generates a small amount of voltage across the terminals (voltage increases as intensity increases), photodiode is semiconductor that responds to light Integrated optical sensing devices - correct answer Combines a light source and light sensing device in one molded integrated package Types of integrated optical sensing devices - correct answer Optical interrupter module/optical reflector module Advantages of one module (integrated optical sensing dev) - correct answer Do not have to worry about the alignment problem, more economical and can be used in mass production Optical scanning systems - correct answer Retro-reflective scanning / opposed optical scanning Retro-reflecting scanning device - correct answer The whole housing in one (when object present open closes and closed opens) Opposed optical scanning device - correct answer Emitter and collector separate (need alignment/longer sense in distance/time delay/ match frequency)