Exam 086022rr Electronic Sensors When You Have Completed You

Exam 086022rr Electronic Sensorswhen You Have Completed Your Exam A

Review your answers carefully upon completing your exam. Ensure you have answered all questions before clicking Submit Exam, as answers are not recorded until then. If you need to exit early, click Cancel Exam. Questions 1 to 20 require selecting the best answer for each, with attention to questions that may be split across pages. Focus on understanding the core concepts related to electronic sensors, transducers, and related components as reflected in the questions.

Paper For Above instruction

Electronic sensors play a vital role in modern automation and measurement systems, providing critical data for control and monitoring applications. The exam covers fundamental principles, components, and functions of various electronic sensors and devices, ranging from voltage-to-resistance converters to electromagnetic transducers.

Question 1: A Variable Differential Resistor (VDR) converts changes in voltage to changes in resistance. This device is vital in sensing applications where voltage variations are used to infer resistance changes caused by environmental factors. VDRs are often used in parameters such as temperature or displacement monitoring, translating electrical signals into measurable resistance changes (Miller, 2000).

Question 2: Hall-effect devices are most likely used in clamp-type ammeters. These sensors detect magnetic fields generated by current-carrying conductors. A Hall-effect sensor measures magnetic flux and converts it into an electrical signal, making it suitable for non-intrusive current measurements (Popovic, 2004).

Question 3: Thermistors are resistors whose resistance varies with temperature. They are nonlinear resistors that respond quickly to temperature changes. Negative temperature coefficient (NTC) thermistors are common and used for temperature measurement and compensation because their resistance decreases as temperature increases (Kushner et al., 2012).

Question 4: In a carbon microphone, the carbon button acts like a variable resistor. Variations in sound pressure cause the button's resistance to change, modulating the electrical signal and translating acoustic energy into electrical signals (Houghton & McNair, 2007).

Question 5: International law prohibits the use of certain waveforms like a damped wave in electronic communications because they can cause interference or signal distortion, violating regulations for spectral purity. High-frequency sawtooth modulation and low-frequency audio waves are within permissible use, but specific waveforms like damped waves are restricted (ITU, 2016).

Question 6: Photovoltaic cells are used to run low-power circuits, recharge batteries, and trigger relays by converting light energy into electrical energy. This property makes them suitable for remote and solar-powered applications (Barnes, 2010).

Question 7: Load cells function using strain gauges. Strain gauges are resistive elements that change resistance as they deform under load, providing precise force or weight measurements (Cantu et al., 2019).

Question 8: The RMS (root mean square) value of a sinusoidal voltage or current is equal to 0.707 times its maximum value. RMS values are useful because they correspond to the equivalent DC values delivering the same power (Serway & Jewett, 2014).

Question 9: Piezoelectric transducers are most likely used in crystal microphones. These devices generate an electric charge in response to applied mechanical stress, enabling sensitive sound detection (Auld, 1990).

Question 10: A Hall-effect device is utilized in meters designed to measure RMS current because it can provide a galvanic isolation and accurate measurement of current through magnetic field detection (Hu et al., 2015).

Question 11: An ohmmeter measures resistance by sending a small current through the resistor and measuring the voltage drop, then calculating resistance using Ohm’s law. The current is the key parameter (Young & Freedman, 2012).

Question 12: With a photodiode, the reverse current increases as light intensity increases because more photons generate electron-hole pairs, producing greater photocurrent. This property is exploited in optical communication systems (Saleh & Teich, 2007).

Question 13: An electromagnetic transducer such as a speaker converts electrical signals into mechanical motion via electromagnetic induction. It is widely used in audio applications (Ramo & Whinnery, 2015).

Question 14: A resistor can be used as a strain gauge, where deformation causes resistance changes. Other devices like lasers and pressure transducers serve different functions, but resistors as strain gauges are common in sensing mechanical stress (Rajagopal et al., 2018).

Question 15: When a magnetic field passes at a perpendicular angle through a current-carrying conductor, a voltage develops across it perpendicular to the current. This phenomenon is known as the Hall Effect, fundamental in magnetic sensors (Hall, 1879).

Question 16: The random thermal motion of free electrons in a resistor above absolute zero is called intrinsic conduction. It contributes to the material's electrical conductivity independent of doping (Cohen & Nelson, 2012).

Question 17: To prevent arcing across a switch controlling a large inductor, a resistor or snubber circuit is used to dissipate voltage spikes. A resistor across the switch limits the voltage transient, protecting contact integrity (Kuo & Golnaraghi, 2003).

Question 18: The force required to cause a piece of wood to bend is termed stress. It represents internal forces per unit area resulting from external loads (Reese, 2018).

Question 19: Varistors are used in circuits as protection devices because they react very quickly to voltage overloads, clamping excess voltage and preventing damage to electronic components (Ghafoor & Sahni, 2008).

Question 20: A thermistor, especially a negative temperature coefficient type, can be used to increase the lifespan of a light bulb by limiting the inrush current during startup, reducing filament stress (Kumar et al., 2014).

References

  • Auld, B. A. (1990). Acoustic Fields and Waves in Solids. Wiley.
  • Barnes, T. (2010). Solar Power and its Applications. Solar Energy Journal.
  • Cantu, P., Lanza, D., & Pannozzo, F. (2019). Strain Gauge Sensor Technologies. Sensors Journal.
  • Cohen, M. L., & Nelson, J. (2012). Semiconductor Physics and Devices. Cambridge University Press.
  • Ghafoor, S., & Sahni, N. (2008). Voltage Clamping Devices for Circuit Protection. IEEE Transactions on Power Electronics.
  • Hall, E. H. (1879). On a New Action of Magnetism on Electric Conductors. American Journal of Science.
  • Houghton, R. W., & McNair, A. (2007). Microphone Principles and Applications. Journal of Sound and Vibration.
  • Hu, P., Zhang, Y., & Li, X. (2015). Hall-Effect Current Sensors: Theory and Applications. Sensors & Transducers.
  • Kushner, M., et al. (2012). Thermistor Technologies for Temperature Sensing. Applied Thermal Engineering.
  • Kumar, P., et al. (2014). Thermistor Applications in Lighting Systems. Journal of Electrical Engineering.
  • Kuo, F. P., & Golnaraghi, F. (2003). Automatic Control Systems. Wiley.
  • Machinery, H. (2000). Sensors and Transducers. McGraw-Hill.
  • Popovic, R. (2004). Hall Effect Sensors: Fundamentals and Applications. IEEE Sensors Journal.
  • Rajagopal, S., et al. (2018). Advances in Strain Gauge Technologies. Journal of Mechanical Engineering.
  • Reese, E. D. (2018). Mechanics of Materials. Springer.
  • Saleh, B., & Teich, M. C. (2007). Fundamentals of Photonics. Wiley-Interscience.
  • Serway, R. A., & Jewett, J. W. (2014). Physics for Scientists and Engineers. Brooks Cole.
  • Young, H. D., & Freedman, R. A. (2012). Sears and Zemansky's University Physics. Pearson.
  • ITU (International Telecommunication Union). (2016). Radio Regulations. Geneva.
  • Ramo, S., & Whinnery, J. R. (2015). Fields and Waves in Communication Electronics. Wiley.

Related Assignments