Sensors

Question 1

it detects the magnitude of a physical parameter and changes it into a signal that can be processed by the system

Answer 1

sensor

Question 2

an active element of a sensor that is responsible for converting energy from one form to another

Answer 2

transducer

Question 3

type of transducer that coverts physical quantities into mechanical

Answer 3

mechanical transducer

Question 4

type of transducer that coverts physical quantities into electrical

Answer 4

electrical transducer

Question 5

what are the two types of transducer?

Answer 5

mechanical and electrical transducer

Question 6

these sensors require an external power source to operate

Answer 6

active sensors

Question 7

these sensors generate an electric current in response to an external stimulus without the need of additional energy source

Answer 7

passive sensors

Question 8

it detects the temperature of its surroundings and transforms the data into electronic output

Answer 8

temperature sensor

Question 9

Two dissimilar metals in contact form a thermoelectric junction that produces a voltage proportional

Answer 9

thermocouple

Question 10

why does thermoelectric junctions occur in pairs?

Answer 10

Because an electrical circuit must form a closed loop

Question 11

it is a metallic wire wound around a ceramic or glass core and hermetically sealed.

Answer 11

resistance temperature detector/ device (RTD)

Question 12

it is a semiconductor device, available
in probes of different shapes and sizes, whose
resistance changes exponentially with temperature.

Answer 12

thermistors

Question 13

what are the two types of thermistor?

Answer 13

negative temperature coefficients (NTC) and positive temperature coefficients (PTC)

Question 14

this thermistor’s resistance decreases as its temperature increases. it is also commonly used for temperature measurement.

Answer 14

NTC thermistors

Question 15

this thermistor’s resistance increases as its temperature increases and is primarily used for circuit protection.

Answer 15

PTC thermistors

Question 16

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

Answer 16

p-n junction temperature sensor

Question 17

are precision integrated-circuit temperature sensors, whose output voltage is linearly proportional to the Celsius (Centigrade)
temperature.

Answer 17

LM35 temperature sensor

Question 18

It is composed of two or more metal layers having different coefficients of thermal expansion.

Answer 18

bimetallic strip

Question 19

in a bimetallic strip, the layers are permanently bonded together. will its structure deform when the temperature changes? (yes or no)

Answer 19

yes

Question 20

__________ are those sensors that detect electromagnetic radiation in what is generally understood as the broad optical range—from far Infrared to Ultraviolet.

Answer 20

optical sensors

Question 21

this type of optical sensor is a resistor whose resistance depends on the intensity of light.

Answer 21

light dependent resistor
LDR
photoresistor

Question 22

this resistor’s resistance is very high but dramatically drops when exposed to light

Answer 22

light dependent resistor
LDR
photoresistor

Question 23

this is a light-sensitive transistor. one of its types is a photobipolar.

Answer 23

phototransistor

Question 24

it is a device that converts motion into a sequence of digital pulses. By counting a single bit or decoding a set of bits, the pulses can be converted to relative or absolute position measurements.

Answer 24

optical encoder

Question 25

emits a light beam (visible or infrared) from its light-emitting element.

Answer 25

photoelectric sensor

Question 26

a type of photoelectric sensor that is used to detect the light beam reflected from the target

Answer 26

reflective type photoelectric sensor

Question 27

a type of photoelectric sensor that is used to measure the change in light quantity caused by the target crossing the optical axis.

Answer 27

thrubeam type sensor

Question 28

a type of photoelectric sensor that light from the emitting element hits the reflector and returns to the light receiving element. When a target is present, the light is interrupted.

Answer 28

retroreflective type sensor

Question 29

it is a non-contact sensor that detects the presence of an object (often referred to as the “target”) when the target enters the sensor's field.

Answer 29

proximity sensor

Question 30

detection of metallic objects (type of proximity sensor)

Answer 30

inductive sensors

Question 31

Detection of metallic and non-metallic objects (Liquids, plastics, woods). (type of proximity sensor)

Answer 31

capacitive sensors

Question 32

a type of proximity sensor that use light sensitive elements to detect objects.

Answer 32

photoelectric sensors

Question 33

a type of proximity sensor that detects the presence of permanent magnets

Answer 33

magnetic sensors

Question 34

consist of two flat ferromagnetic reeds sealed in an inert atmosphere within a glass capsule.

Answer 34

reed switch

Question 35

A special kind of variable resistor, whose electrical resistance depends on the external magnetic force applied

Answer 35

magneto resistor

Question 36

it is a transducer used for measuring linear displacement. It consists of primary and secondary windings and a movable iron core. It functions much like a transformer, where voltages are induced in the secondary coil in response to excitation in the primary coil.

Answer 36

linear variable differential transformer/transducer

Question 37

The simplest kind of displacement sensor is a mechanical switch which returns one bit of information: touching or not touching.

Answer 37

mechanical switch

Question 37

these are devices that are activated by an external magnetic field. The output signal from it is the function of magnetic field density around the device.

Answer 37

hall effect sensor

Question 38

The most common transducer for experimentally measuring strain in a mechanical component is the bonded metal foil strain gage

Answer 38

strain gauge/strain gage

Question 39

what are the 3 types of strain gage assembly?

Answer 39

uniaxial biaxial strain gage rosette

Question 40

devices that measure acceleration, which is the rate of change of the velocity of an object.

Answer 40

accelerometer

Question 41

Some materials (such as natural quartz crystal, silicon dioxide, barrium titanite, lead zirconate titanate (PZT)), called piezo crystals, produce a charge in response to a force (or deformation) applied to them.

Answer 41

piezoelectric accelerometer

Question 42

A _________ can be built by using a permanent magnet as a mass on a spring or cantilever beam and sense the field of the permanent magnet using a Hall element or magnetoresistive sensor

Answer 42

magnetic accelerometers

Question 43

it is a sensor or a transducer that converts a load or force acting on it into an electronic signal. This electronic signal can be a voltage change, current change or frequency change depending on the type of load cell and circuitry used

Answer 43

load cell

Question 44

a process technology used to create tiny integrated devices or systems that combine mechanical and electrical components.

Answer 44

micro-electromechanical systems (MEMS)

Question 45

have the ability to sense, control and actuate on the micro scale, and generate effects on the macro scale.

Answer 45

MEMS

Question 46

One of the simplest and least expensive ways to measure rotational or linear motion.

Answer 46

potentiometer

Question 47

made of a pyroelectric sensor (which you can see above as the round metal can with a rectangular crystal in the center), which can detect levels of infrared radiation. Everything emits some low level radiation, and the hotter something is, the more radiation is emitted

Answer 47

PIR sensor

Question 48

sends out a high-frequency sound pulse and then times how long it takes for the echo of the sound to reflect back. The sensor has 2 openings on its front. One opening transmits ultrasonic waves, (like a tiny speaker), the other receives them, (like a tiny microphone)

Answer 48

ultrasonic distance sensor

Question 49

The effect by which a thermoelectric junction of dissimilar metals produces a voltage relative to temperature

Answer 49

seebeck effect