Skoog/Holler/CrouchChapter 1Principles of Instrumental Analysis, 7thed.1CHAPTER 11-1.A transducer is a device that converts chemical or physical information into an electricalsignal or the reverse. The most common input transducers convert chemical or physicalinformation into a current, voltage, or charge, and the most common output transducersconvert electrical signals into some numerical form.1-2.The information processor in a visual color measuring system is the human brain.1-3.The detector in a spectrograph is a photographic film or plate.1-4.Smoke detectors are of two types: photodetectors and ionization detectors. Thephotodetectors consist of a light source, such as a light-emitting diode (LED) and aphotodiode to produce a current proportional to the intensity of light from the LED.When smoke enters the space between the LED and the photodiode, the photocurrentdecreases, which sets off an alarm. In this case the photodiode is the transducer.In ionization detectors, which are the typical battery-powered detectors found in homes, asmall radioactive source (usually Americium) ionizes the air between a pair of electrodes.When smoke enters the space between the electrodes, the conductivity of the ionized airchanges, which causes the alarm to sound. The transducer in this type of smoke detectoris the pair of electrodes and the air between them.1-5.Adata domainis one of the modes in which data may be encoded. Examples of datadomain classes are the analog, digital and time domains. Examples of data domains arevoltage, current, charge, frequency, period, number.Preview Mode
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