Question of the Week - Answer 211011https://learnemc.com/qotw-211011

EMC Question of the Week: October 11, 2021 A person wearing leather shoes shuffles across a polyester carpet on a dry day collecting a significant charge. The polarity of the charge is positive is negative depends on the season depends on the...

Question of the Week - Answer 181112https://learnemc.com/qotw-181112

EMC Question of the Week: November 12, 2018 Heatsinks mounted over the top of high-speed microprocessors should generally be connected to the circuit board's ground plane connected to the chassis floated (i.e. not grounded) none of the above Answer The...

Question of the Week - Answer 171204https://learnemc.com/qotw-171204

EMC Question of the Week: December 4, 2017 Unlike electric currents, magnetic currents can flow on the surfaces of insulators always flow in closed loops produce magnetic fields don't exist in the real world Answer The best answer is "d". The concepts...

Question of the Week - Answer 190204https://learnemc.com/qotw-190204

EMC Question of the Week: February 4, 2019 Leakage inductance in a common-mode choke consisting of two wires wound around the same ferrite core results in leakage current equivalent series resistance radiated emissions differential-mode inductance...

Question of the Week - Answer 200302https://learnemc.com/qotw-200302

EMC Question of the Week: March 2, 2020 Electrically small loop antennas are widely used to detect and measure electric fields magnetic fields far-field radiation conducted emissions Answer The correct answer is "b". Electrically small loops produce a...

Question of the Week - Answer 200907https://learnemc.com/qotw-200907

EMC Question of the Week: September 7, 2020 In order to prevent differential-mode to common-mode conversion, what property of an electrical connector needs to be matched to the signal conductors on both ends? wave velocity characteristic impedance...

Question of the Week - Answer 250811https://learnemc.com/qotw-250811

EMC Question of the Week: August 11, 2025 Which of the following is NOT one of Maxwell's equations? Ohm's Law Gauss's Law Ampere's Law Faraday's Law Answer The best answer is “a.” Ohm's law is an equation from circuit theory. It's field-theory...

Question of the Week - Answer 170417https://learnemc.com/qotw-170417

EMC Question of the Week: April 27, 2017 Interference between an AM car radio (1.5 MHz) and an overhead power line is likely due to, conducted coupling electric field coupling magnetic field coupling radiation coupling Answer The correct answer is "b"....

Question of the Week - Answer 170313https://learnemc.com/qotw-170313

EMC Question of the Week: March 13, 2017 Quasi-peak values are always, equal-to or less-than peak values equal-to or less-than average values both "a" and "b" none of the above Answer The correct answer is "a". Quasi-peak values are always less than or...

Question of the Week - Answer 201123https://learnemc.com/qotw-201123

EMC Question of the Week: November 23, 2020 Which of the following EMC test standards does NOT describe a procedure for measuring radiated emissions? ANSI C63.4 CISPR 32 IEC 61000-4-2 MIL-STD-461G Answer The best answer is "c". IEC 61000-4-2 is a...

Question of the Week - Answer 180903https://learnemc.com/qotw-180903

EMC Question of the Week: September 3, 2018 Due to the skin effect, at high frequencies the resistance of conductors in a transmission line increases with increasing frequency decreases with increasing frequency exhibits a "sweet spot" where the...

Question of the Week - Answer 220801https://learnemc.com/qotw-220801

EMC Question of the Week: August 1, 2022 For optimum performance in radiated emissions testing, the circuit ground in high-speed printed circuit boards should normally be well-connected to the chassis ground connected to chassis ground at a single...

Question of the Week - Answer 170612https://learnemc.com/qotw-170612

EMC Question of the Week: June 12, 2017 The best computer modeling tool for calculating the electrical balance of a transmission line is a, 2D static field solver 3D static field solver 3D full-wave field solver SPICE Answer The correct answer is "a"....

Question of the Week - Answer 260518https://learnemc.com/qotw-260518

EMC Question of the Week: May 18, 2026 One advantage of routing high-speed differential signals on microstrip trace pairs as opposed to stripline trace pairs is that microstrip trace pairs generally radiate less take up less space have better balance...

Question of the Week - Answer 190311https://learnemc.com/qotw-190311

EMC Question of the Week: March 11, 2019 To an EMC engineer, NEXT is an acronym for Near-End Crosstalk Nominal Extraneous Transmissions National Exchange Treaty Nuclear Excitation Test Answer The correct answer is "a." Crosstalk is a measure of the...

Question of the Week - Answer 180409https://learnemc.com/qotw-180409

EMC Question of the Week: April 9, 2018 Which of the following statements about earth ground is generally true? all current ultimately flows to earth ground for safety reasons, all electronic systems require an earth ground ground conductors in a...

Question of the Week - Answer 200406https://learnemc.com/qotw-200406

EMC Question of the Week: April 6, 2020 According to IEC 60417, which of the following is NOT a ground symbol? Answer The correct answer is "c". This inverted triangle symbol is commonly used to represent a local circuit reference on a printed circuit...

Question of the Week - Answer 240812https://learnemc.com/qotw-240812

EMC Question of the Week: August 12, 2024 Three of the four electromagnetic coupling mechanisms are proportional to the source current. Which one is proportional to the source voltage? conducted coupling electric-field coupling magnetic-field coupling...

Question of the Week - Answer 241028https://learnemc.com/qotw-241028

EMC Question of the Week: October 28, 2024 Which 2-port S-parameter value is consistent with a vector network analyzer measurement of a lossless cable that connects Port 1 to Port 2? |S­11| = 0 dB |S­11| = 3 dB |S­21| = 0 dB |S­12| = -∞ dB Answer The...

Question of the Week - Answer 210719https://learnemc.com/qotw-210719

EMC Question of the Week: July 19, 2021 In 12-V (or 42-V) automotive components, the circuit board's "ground" planes should normally be tied to any existing nearby chassis ground through capacitors capacitors in parallel with a resistance capacitors in...

Question of the Week - Answer 211101https://learnemc.com/qotw-211101

EMC Question of the Week: November 1, 2021 A dot on an inductor package indicates the location of the input current terminal external winding terminal shield connection terminal core Answer The best answer is “b.” When inductors have several layers of...

Question of the Week - Answer 180806https://learnemc.com/qotw-180806

EMC Question of the Week: August 6, 2018 A signal traveling on a 120-ohm wire pair passes through a connector with a characteristic impedance of 50 ohms before continuing along on another 120-ohm wire pair. At frequencies where the connector is short...

Question of the Week - Answer 210125https://learnemc.com/qotw-210125

EMC Question of the Week: January 25, 2021 A 1-kΩ resistor in series with a CMOS input pin on a microcontroller can help to improve conducted emissions radiated emissions ESD immunity all of the above Answer The best answer is “d.” Internal noise...

Question of the Week - Answer 220502https://learnemc.com/qotw-220502

EMC Question of the Week: May 2, 2022 A digital signal source drives a 20-cm microstrip trace terminated with a CMOS input at 10 Mbps. The sum of the trace capacitance and the input capacitance is 18 pF. Which component below would be a good choice to...

Question of the Week - Answer 240701https://learnemc.com/qotw-240701

EMC Question of the Week: July 1, 2024 Most TEM cells used for EM emissions and immunity testing have a characteristic impedance equal to 50 Ω 75 Ω 100 Ω 377 Ω Answer The best answer is “a". Most TEM cells have a 50-Ω characteristic impedance in order...

Question of the Week - Answer 250303https://learnemc.com/qotw-250303

EMC Question of the Week: March 3, 2025 Two RLCG lumped parameter models for a twisted wire pair transmission line are shown in the figure. One of them uses one R and one L value to model the resistance and inductance per unit length. The other uses...

Question of the Week - Answer 251222https://learnemc.com/qotw-251222

EMC Question of the Week: December 22, 2025 In a waveguide made of a single conductor such as a hollow tube or a rectangular duct, electromagnetic energy can only propagate at one frequency at specific discrete frequencies below a certain cutoff...

Question of the Week - Answer 260629https://learnemc.com/qotw-260629

EMC Question of the Week: June 29, 2026 A single-ended 1-Gbps digital signal is routed across a circuit board (10 cm) on a microstrip trace that is 0.25 mm above the return plane. To meet EMC and signal integrity requirements, this signal trace should...

Question of the Week - Answer 210621https://learnemc.com/qotw-210621

EMC Question of the Week: June 21, 2021 You're in an aluminum canoe in the middle of a large lake when a thunderstorm approaches. To protect yourself from lightning, you should row towards shore swim towards shore turn the canoe over and get under it...

Question of the Week - Answer 241104https://learnemc.com/qotw-241104

EMC Question of the Week: November 4, 2024 At data rates from 1 Mbps to 100 Mbps most of the signal attenuation/dispersion in long microstrip traces and long unshielded twisted wire pairs (e.g., CAT5e) is typically due to conductor loss dielectric loss...

Question of the Week - Answer 180716https://learnemc.com/qotw-180716

EMC Question of the Week: July 16, 2018 Gauss’ Law, ∇∙D = ρ, basically tells us that lines of electric flux have no beginning or end start and stop on electric charge are stronger in permeable materials are stronger in liquids Answer The correct answer...

Question of the Week - Answer 220509https://learnemc.com/qotw-220509

EMC Question of the Week: May 9, 2022 For a given magnetic field strength, the voltage detected by a magnetic-field probe (electrically small loop or coil) connected to a 50-Ω spectrum analyzer is independent of frequency proportional to frequency (a)...

Question of the Week - Answer 240603https://learnemc.com/qotw-240603

EMC Question of the Week: June 3, 2024 The walls of a particular shielding enclosure have a nominal thickness of 60 mils. This is equal to 0.06 inches 0.17 inches 6 mm 6 cm Answer The correct answer is “a.” One mil is equal to 0.001 inches. This may be...

Question of the Week - Answer 260126https://learnemc.com/qotw-260126

EMC Question of the Week: January 26, 2026 The TDR output waveform shown in the figure indicates a discontinuity 1.5 meters down the line. The discontinuity appears to be a short circuit open circuit series inductance series capacitance Answer The best...

Question of the Week - Answer 240916https://learnemc.com/qotw-240916

EMC Question of the Week: September 16, 2024 The yellow components on the circuit board in the figure are in series with some of the low-speed I/O traces. These components are probably resistors capacitors inductors TVS diodes Answer The best answer is...

Question of the Week - Answer 170403https://learnemc.com/qotw-170403

EMC Question of the Week: April 3, 2017 At 100 MHz, the plane-wave shielding effectiveness of aluminum foil, is close to 0 dB is approximately 20 dB is more than 100 dB could be less than 0 dB Answer The correct answer is "c". Unlike the shielding...

Question of the Week - Answer 171218https://learnemc.com/qotw-171218

EMC Question of the Week: December 18, 2017 A signal traveling on a 50-ohm cable passes through a connector with a characteristic impedance of 150 ohms before continuing along another 50-ohm cable. At frequencies where the connector is short relative...

Question of the Week - Answer 180528https://learnemc.com/qotw-180528

EMC Question of the Week: May 28, 2018 When the DC saturation current of a ferrite bead is exceeded, its impedance at high frequencies decreases significantly increases significantly is mostly unaffected is unaffected in magnitude, but shifts in phase...

Question of the Week - Answer 190603https://learnemc.com/qotw-190603

EMC Question of the Week: June 3, 2019 Which of the following N-port network parameters is equal to the voltage reflection coefficient at one of the ports? S11 S12 Z11 Z12 Answer The correct answer is "a". S-parameters relate the voltage waves...

Question of the Week - Answer 220425https://learnemc.com/qotw-220425

EMC Question of the Week: April 25, 2022 Generally, to meet radiated emissions requirements, circuit board traces carrying digital signals faster than 1 Mbps should NOT make 90-degree turns cross over gaps in the ground plane have unmatched...

Question of the Week - Answer 220214https://learnemc.com/qotw-220214

EMC Question of the Week: February 14, 2022 Nearly all electronic keyboards are protected from electrostatic discharge by TVS diodes ESD rings a plastic membrane antistatic keys Answer The correct answer is “c.” Keyboards typically have a plastic...

Question of the Week - Answer 221010https://learnemc.com/qotw-221010

EMC Question of the Week: October 10, 2022 If a resistor network is labeled 101, the value of each resistor in the network is likely to be 1 Ω 10 Ω 100 Ω 101 Ω Answer The correct answer is “c.” When the code used to label a resistor consists of 3...

Question of the Week - Answer 230424https://learnemc.com/qotw-230424

EMC Question of the Week: April 24, 2023 When connecting a solder pad or a connector pin to a solid plane in a circuit board, it is not unusual to make the connection using four spokes as illustrated in the figure. This is called a thermal relief...

Question of the Week - Answer 240819https://learnemc.com/qotw-240819

EMC Question of the Week: August 19, 2024 A particular source delivers 2.0 mW of power to a 50-Ω receiver when they are directly connected. When they are connected through 20 cm of 50-Ω coaxial cable, the received power is only 1.8 mW due to cable...

Question of the Week - Answer 191118https://learnemc.com/qotw-191118

EMC Question of the Week: November 18, 2019 A ferrite bead should be placed in series with the ground connection on analog-to-digital converters on stable voltage references when the app note specifies it all of the above none of the above Answer The...

Question of the Week - Answer 241111https://learnemc.com/qotw-241111

EMC Question of the Week: November 11, 2024 When is the decoupling capacitor, trace, and via placement indicated in this figure appropriate? almost always when the VDD and GND planes are closely spaced when the VDD and GND planes are widely spaced...

Question of the Week - Answer 250519https://learnemc.com/qotw-250519

EMC Question of the Week: May 19, 2025 The primary purpose of printed circuit board shields is to reduce conducted coupling radiated coupling near-field coupling power bus noise Answer The best answer is “c.” Shielding the circuits/components on a...

Question of the Week - Answer 260119https://learnemc.com/qotw-260119

EMC Question of the Week: January 19, 2026 In order for electric-field shields to be effective, they must be conductive grounded a skin depth or more thick all of the above Answer The best answer is “a.” Electric field shields work by allowing charge...

Question of the Week - Answer 220418https://learnemc.com/qotw-220418

EMC Question of the Week: April 18, 2022 In terms of shielding effectiveness, the most important dimension of a slot or seam in a shielding enclosure is generally its length thickness depth area Answer The best answer is “a.” Length is by far the most...

Question of the Week - Answer 211122https://learnemc.com/qotw-211122

EMC Question of the Week: November 22, 2021 If a plane wave propagating in a 50-Ω TEM cell has an electric field strength of 100 V/m, the magnetic field strength is approximately 0 A/m 0.27 A/m 2.0 A/m 3.77 A/m Answer The correct answer is “b.” The...