1RF stands for what?
Radio Frequency
2What is the RF frequency range?
20 kHz to 300 GHz
3As frequency increases, what happens to wavelength?
It gets shorter (inversely proportional)
4What RF band is used for submarine communication?
Extremely Low Frequency (ELF)
5What RF band is used for navigation and wireless heart rate sensors?
Very Low Frequency (VLF)
6What RF band is used for AM broadcasting?
Medium Frequency (MF)
7What RF band is used for FM broadcasting and TV broadcasting?
Very High Frequency (VHF)
8What RF band is used for WiFi, Bluetooth, GPS, and mobile phones?
Ultra High Frequency (UHF)
9What do transducers do?
Convert one form of energy to another
10What does a microphone convert?
Sound energy to electrical energy
11What does a speaker convert?
Electrical energy to sound energy
12What does a solar cell convert?
Light energy to electrical energy
13What is a sensor?
A device that detects a physical variable and converts it into a signal
14What type of sensor requires external power?
Passive sensor
15Give an example of a passive sensor
RTD or Strain Gauge
16What type of sensor produces voltage without external power?
Active sensor
17Give an example of an active sensor
Thermocouple or Piezoelectric sensor
18What device amplifies a sensor signal into 4–20 mA or 1–5 V?
Transmitter
19A sensor gives what type of output signal?
Continuous analog signal
20A switch gives what type of output?
ON/OFF only
21What does a photodiode do?
Converts light into electrical current
22What does a photoresistor (LDR) do when light increases?
Its resistance decreases
23What does a phototransistor do?
Uses light to control current
24What do CCD or CMOS sensors convert?
Light into a digital image
25What is the formula for pressure?
Force divided by area
26What are common pressure units?
Pascal, Bar, PSI
27What is the piezoelectric effect?
A material generates electrical charge when stressed
28What type of pressure sensor changes resistance?
Piezoresistive sensor
29What type of pressure sensor measures deformation?
Strain Gauge
30What type of pressure sensor changes capacitance?
Capacitive sensor
31Pressure measured against atmosphere is called what?
Gauge pressure
32Pressure measured against a perfect vacuum is called what?
Absolute pressure
33Pressure between two points is called what?
Differential pressure
34What does an accelerometer measure?
Acceleration or movement
35What does a gyroscope measure?
Rotation
36What does a magnetometer measure?
Magnetic field
37What does MEMS stand for?
Micro ElectroMechanical Systems
38What does a MEMS accelerometer detect?
Movement by changing capacitance
39What does a MEMS gyroscope measure?
Angular rotation
40What does PIR stand for?
Passive Infrared
41What does a PIR sensor detect?
Infrared radiation (body heat)
42What material does a PIR sensor use to generate voltage?
Pyroelectric elements
43What lens increases PIR detection range?
Fresnel lens