BRAE 328 || Faultless Answers 100%.
Sensors correct answers The device which actually does the measuring. Converts the physical
state (temperature, pressure...) into something that can be processed (voltage, resistance...)
Voltage Divider equation correct answers Vout = V1R2/(R1 + R2)
Examples of resistive device sensors correct answers Strain gauges, weigh-scale load cells,
pressure sensors, relative humidity, resistance temperature devices, and thermistors
Problems with using a voltage divider correct answers R1 must be precisely known, the
voltmeter must have a resistance much greater than R2
Wheatstone Bridge Equation correct answers Vab = (R2/(R1+R2) - R4/(R3+R4))Vin
Strain gauge (how it works) correct answers A long length of conductor arranged in a zigzag
pattern on a membrane. When it is stretched, its resistance is increased.
What causes resistance to increase in a strain gauge? correct answers Tension
How to create a AC Wheatstone bridge correct answers Replace the DC with ACa and resistance
with impedance.
Balanced Wheatstone Bridge Equation correct answers R1/R2=R3/R4
How to create a Load Cell correct answers Place four strain gauges
How to cancel out temperature change when creating a Wheatstone bridge with strain gauges.
correct answers Strain gauge is located in the location of R4. Place a dummy strain gauge in
place of R2. So the R4 location is stressed and the R2 location is unstressed.
, Resistive Temperature Detectors (RTD) correct answers Used to measure temperature by
correlating the resistance of the RTD element with temperature.
How is a RTD created? correct answers A length of fine coiled wire wrapped around a ceramic or
glass core.
Thermocouple correct answers Fuse two dissimilar metals together. This gives a constant
potential difference of a few mV
Resistive Soil Moisture Sensor correct answers Made of two exposed electrodes. The more water
the soil contains, the lower the resistance between the two electrodes
Why are resistive sensors sometime unreliable? correct answers Electrodes can degrade and
oxidize over time
Capacitive soil sensors correct answers Made of two electrodes that are insulated. The two
electrodes and the soil form a capacitor. The higher the water content, the higher the capacitance.
MEMS Sensors correct answers Micro-electro-mechanical system: miniature transducers created
using IC fabrication processes
Example of a MEMS Sensor correct answers Accelerometer, gyroscope (angular acceleration)
What are the three types of sensors? correct answers Thermal sensors, mechanical sensors, and
optical sensors
Incremental motor encoder correct answers Counts pulses from 1 to n. The number of pulses
defines the resolution
Sensors correct answers The device which actually does the measuring. Converts the physical
state (temperature, pressure...) into something that can be processed (voltage, resistance...)
Voltage Divider equation correct answers Vout = V1R2/(R1 + R2)
Examples of resistive device sensors correct answers Strain gauges, weigh-scale load cells,
pressure sensors, relative humidity, resistance temperature devices, and thermistors
Problems with using a voltage divider correct answers R1 must be precisely known, the
voltmeter must have a resistance much greater than R2
Wheatstone Bridge Equation correct answers Vab = (R2/(R1+R2) - R4/(R3+R4))Vin
Strain gauge (how it works) correct answers A long length of conductor arranged in a zigzag
pattern on a membrane. When it is stretched, its resistance is increased.
What causes resistance to increase in a strain gauge? correct answers Tension
How to create a AC Wheatstone bridge correct answers Replace the DC with ACa and resistance
with impedance.
Balanced Wheatstone Bridge Equation correct answers R1/R2=R3/R4
How to create a Load Cell correct answers Place four strain gauges
How to cancel out temperature change when creating a Wheatstone bridge with strain gauges.
correct answers Strain gauge is located in the location of R4. Place a dummy strain gauge in
place of R2. So the R4 location is stressed and the R2 location is unstressed.
, Resistive Temperature Detectors (RTD) correct answers Used to measure temperature by
correlating the resistance of the RTD element with temperature.
How is a RTD created? correct answers A length of fine coiled wire wrapped around a ceramic or
glass core.
Thermocouple correct answers Fuse two dissimilar metals together. This gives a constant
potential difference of a few mV
Resistive Soil Moisture Sensor correct answers Made of two exposed electrodes. The more water
the soil contains, the lower the resistance between the two electrodes
Why are resistive sensors sometime unreliable? correct answers Electrodes can degrade and
oxidize over time
Capacitive soil sensors correct answers Made of two electrodes that are insulated. The two
electrodes and the soil form a capacitor. The higher the water content, the higher the capacitance.
MEMS Sensors correct answers Micro-electro-mechanical system: miniature transducers created
using IC fabrication processes
Example of a MEMS Sensor correct answers Accelerometer, gyroscope (angular acceleration)
What are the three types of sensors? correct answers Thermal sensors, mechanical sensors, and
optical sensors
Incremental motor encoder correct answers Counts pulses from 1 to n. The number of pulses
defines the resolution
