Sensors Flashcards
it detects the magnitude of a physical parameter and changes it into a signal that can be processed by the system
sensor
an active element of a sensor that is responsible for converting energy from one form to another
transducer
type of transducer that coverts physical quantities into mechanical
mechanical transducer
type of transducer that coverts physical quantities into electrical
electrical transducer
what are the two types of transducer?
mechanical and electrical transducer
these sensors require an external power source to operate
active sensors
these sensors generate an electric current in response to an external stimulus without the need of additional energy source
passive sensors
it detects the temperature of its surroundings and transforms the data into electronic output
temperature sensor
Two dissimilar metals in contact form a thermoelectric junction that produces a voltage proportional
thermocouple
why does thermoelectric junctions occur in pairs?
Because an electrical circuit must form a closed loop
it is a metallic wire wound around a ceramic or glass core and hermetically sealed.
resistance temperature detector/ device (RTD)
it is a semiconductor device, available
in probes of different shapes and sizes, whose
resistance changes exponentially with temperature.
thermistors
what are the two types of thermistor?
negative temperature coefficients (NTC) and positive temperature coefficients (PTC)
this thermistor’s resistance decreases as its temperature increases. it is also commonly used for temperature measurement.
NTC thermistors
this thermistor’s resistance increases as its temperature increases and is primarily used for circuit protection.
PTC thermistors
In this temperature-sensor the forward ac voltage change or the forward ac current change at the pn junction diode due to the temperature change is measured for a constant amplitude of superimposed ac small signal of current δI or voltage δV, respectively, on the constant forward dc current I0
p-n junction temperature sensor
are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade)
temperature.
LM35 temperature sensor
It is composed of two or more metal layers having different coefficients of thermal expansion.
bimetallic strip
in a bimetallic strip, the layers are permanently bonded together. will its structure deform when the temperature changes? (yes or no)
yes
__________ are those sensors that detect electromagnetic radiation in what is generally understood as the broad optical range—from far Infrared to Ultraviolet.
optical sensors