Question 1

Digital circuits and logic rules: do digital circuits obey Boolean logic?  Evaluate the claim: “A digital circuit will not obey a set of logic rules.” In the context of Boolean algebra, logic families, and truth tables, determine whether the stateme…

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Introduction / Context: Digital electronics is grounded in Boolean algebra. Gates, flip-flops, and combinational/sequential circuits are designed to implement precise logical relationships. This item checks conceptual clarity about whether digital circuits are expected to follow defined logic rules. Given Data / Assumptions: Ideal operation assumes valid input levels within specified thresholds. Timing requirements (setup, hold, propagation) are met. Supply rails, temperature, and loading remain within data sheet limits. Concept / Approach: Truth tables and Boolean expressions define how outputs should respond to inputs. Within specified operating conditions, gate-level hardware reliably enforces these rules. Deviations arise only when constraints are violated (e.g., undefined inputs, excessive fanout, noise, or timing violations), which does not negate the existence of the rules—only the validity of the operating point. Step-by-Step Solution: Recall that gates implement Boolean functions by design (e.g., OR, AND, NOT).Recognize that logic rules underpin minimization, Karnaugh maps, and synthesis.Understand that violations occur only when specifications are not met.Therefore the claim that digital circuits do not obey logic rules is false. Verification / Alternative check: Simulate a circuit in a HDL or measure with a logic analyzer; outputs match truth tables when operated within specs. Why Other Options Are Wrong: Correct: Incorrect because digital hardware is specifically built to obey logic.Only true for analog ICs / Only true above 10 MHz: Irrelevant distractors; analog ICs are not digital gates, and frequency alone does not nullify logic rules. Common Pitfalls: Mistaking symptoms of bad design (glitches from timing violations, improper termination) as evidence that logic rules are invalid. Final Answer: Incorrect

Question 2

Positive logic voltage levels: could logic LOW be in the 0 V to 0.8 V range?  Consider a typical positive logic family (e.g., TTL). Assess whether a logic LOW input level could lie between 0 V and 0.8 V.

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Introduction / Context: Logic families specify input thresholds for LOW and HIGH to guarantee proper recognition. For TTL-compatible inputs in positive logic, a LOW level is recognized if it is below a defined maximum voltage, commonly around 0.8 V. Given Data / Assumptions: Positive logic: higher voltage represents logic 1, lower voltage represents logic 0. Representative TTL thresholds: VIL(max) ≈ 0.8 V, VIH(min) ≈ 2.0 V at 5 V supply. CMOS families have different thresholds but also define clear LOW/HIGH windows. Concept / Approach: A statement that a logic LOW “could be between 0 V and 0.8 V” aligns with many TTL specs: any voltage in that window is guaranteed to be read as LOW. Values in the undefined window between VIL(max) and VIH(min) are not guaranteed; above VIH(min) is recognized as HIGH. Thus, the claim is correct for compatible families and exemplifies the concept of noise margins. Step-by-Step Solution: Identify logic family and its thresholds from data sheets.Map the stated range (0–0.8 V) to VIL(max) for TTL.Confirm that any value in the stated range is a valid logic LOW.Conclude that the statement is accurate in the intended context. Verification / Alternative check: Measure an input while varying voltage: below 0.8 V a TTL input reliably reads as 0; above 2.0 V it reads as 1; in between is undefined. Why Other Options Are Wrong: Incorrect: Conflicts with well-known TTL thresholds.Applies only to CMOS / only to 3.3 V: Misapplies the thresholds; the example range is characteristic of TTL at 5 V. Common Pitfalls: Assuming the exact numbers apply to all families; always consult the specific data sheet for precise limits. Final Answer: Correct

Question 3

SMT acronym in electronics manufacturing: what does “SMT” stand for?  Evaluate the statement: “SMT stands for small-to-medium technology.” Determine whether this is a correct expansion of the industry acronym.

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Introduction / Context: SMT is a ubiquitous term in electronics manufacturing. Knowing the correct expansion helps learners connect component packaging, assembly techniques, and PCB design constraints (pads, reflow profiles) to the broader production process. Given Data / Assumptions: Common industry acronyms are used without definition in datasheets and application notes. The question asks you to validate a specific expansion of “SMT.” Concept / Approach: SMT correctly stands for Surface-Mount Technology, a method where components are mounted directly onto the surface of printed circuit boards rather than using through-hole leads. The phrase “small-to-medium technology” is not a recognized term in electronics assembly and is incorrect in this context. Step-by-Step Solution: Recall standard manufacturing terms: SMT (Surface-Mount Technology), SMD (Surface-Mount Device), THT (Through-Hole Technology).Compare the offered phrase with the recognized definition.Identify the mismatch: “small-to-medium technology” is not used in this domain.Conclude the statement is incorrect. Verification / Alternative check: Cross-reference component datasheets or IPC standards where SMT/SMD terminology is consistently defined. Why Other Options Are Wrong: Correct: Not true; the correct expansion is Surface-Mount Technology.Packaging-only / transistor sizing: These are unrelated or overly narrow interpretations. Common Pitfalls: Confusing SMT with SMD; SMT is the technique, SMD is the device. Also, assuming “SMT” relates to device size rather than mounting style. Final Answer: Incorrect

Question 4

What constitutes a CPU? Does it consist of memory and outputs?  Assess the statement: “The CPU (Central Processing Unit) is composed of memory and outputs.” Decide if this is a correct description of CPU composition.

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Introduction / Context: Understanding what a CPU is versus what surrounds it (memory and I/O) is foundational in computer architecture. The CPU executes instructions using internal functional blocks and communicates with, but does not equal, the memory and output peripherals. Given Data / Assumptions: “CPU” refers to the processing core of a computer system. Memory (RAM/ROM) and I/O (inputs/outputs) are external subsystems, though they may be integrated on the same chip in microcontrollers. Internal CPU elements include ALU, control unit, registers, and buses. Concept / Approach: A CPU comprises an arithmetic logic unit, control logic (instruction decode/sequencing), and a register file; it may also include caches. Memory and I/O are separate architectural elements accessed via buses. Even in SoCs or microcontrollers, we distinguish the CPU core from the on-chip memory and peripherals; integration does not redefine the CPU’s composition. Step-by-Step Solution: List CPU elements: ALU, control unit, registers, possibly caches.List non-CPU elements: main memory, secondary storage, input/output devices.Note that communication occurs via bus interfaces and controllers.Conclude the statement is incorrect: a CPU is not “memory and outputs.” Verification / Alternative check: Block diagrams in architecture textbooks show CPU as a distinct block interfacing with memory and I/O, not consisting of them. Why Other Options Are Wrong: Correct: Mischaracterizes CPU composition.Only true for microcontrollers / Von Neumann: Even then, the CPU core is distinct from memory and I/O blocks. Common Pitfalls: Equating “integrated on one chip” with “part of the CPU.” Integration does not change architectural roles. Final Answer: Incorrect

Question 5

Digital techniques in telecommunications: are they used?  Evaluate the statement: “Telecommunications systems do not use digital techniques.” Determine whether this statement aligns with modern communication practices.

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Introduction / Context: Modern telecommunications—from cellular networks and fiber optics to Wi-Fi and satellite—relies heavily on digital modulation, coding, and switching. The statement claims the opposite; this item checks your awareness of the digital revolution in communications. Given Data / Assumptions: We consider contemporary telecom systems: 4G/5G, optical transport, VoIP, WLAN, and satellite links. Digital techniques include modulation (QAM/PSK), error-correcting codes, packet switching, and DSP. Analog techniques exist historically and at certain interfaces, but the end-to-end system is dominantly digital. Concept / Approach: Telecom systems digitize information for robustness, compression, multiplexing, and encryption. Digital modulation and coding increase spectral efficiency and reliability. Network cores are packet-switched and IP-based. Therefore, saying telecommunications does not use digital techniques is inaccurate. Step-by-Step Solution: Identify key digital building blocks: ADC/DAC, DSP, FEC, packet routing.Survey major networks: cellular, optical, and Wi-Fi are digital.Recognize residual analog portions (e.g., RF front-ends) do not negate digital processing dominance.Conclude the statement is incorrect. Verification / Alternative check: Review standards (3GPP, IEEE 802.11, ITU-T); specifications are digital and packet-centric. Why Other Options Are Wrong: Correct: Contradicted by virtually all modern systems.Legacy-only / radio-only caveats: Misleading; even legacy systems were progressively digitized (e.g., PCM in telephony). Common Pitfalls: Assuming “RF” implies analog end-to-end; RF carries digitally modulated symbols processed by DSP. Final Answer: Incorrect

Question 6

Binary numeral system: how many symbols are there?  Evaluate the statement: “In a binary system there are only two symbols.” Decide whether this description of the base-2 numeral system is accurate.

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Introduction / Context: Positional numeral systems are characterized by their base (radix) and the number of distinct digit symbols. Binary is base-2 and is the foundation of digital electronics. This item tests recognition of a fundamental property of the binary system. Given Data / Assumptions: Binary digits (bits) are the atomic symbols used in base-2 numeration. Digital logic encodes these symbols as valid LOW and HIGH levels. No special coding (e.g., Gray, BCD) alters the number of symbols of the base itself. Concept / Approach: By definition, a base-r system uses r unique digit symbols. For base-2, r = 2, hence two symbols. In digital practice these symbols are represented by two valid voltage/current ranges. All binary numbers, signed or unsigned, are sequences of these two symbols, even if interpreted differently by higher-level formats. Step-by-Step Solution: Recall the definition: binary = base-2.Therefore, it uses exactly two digit symbols.Map to hardware: logic 0 and logic 1 correspond to two valid level ranges.Conclude the statement is correct. Verification / Alternative check: Compare with other bases: octal (8 symbols 0–7), decimal (10 symbols 0–9), hexadecimal (16 symbols 0–9 and A–F). Why Other Options Are Wrong: Incorrect: Contradicts the definition of base-2.Signed/floating qualifiers: Representation formats do not change the base’s symbol count. Common Pitfalls: Confusing encoding schemes (e.g., BCD, Gray) with the underlying base; these are alternative mappings built from the same two symbols. Final Answer: Correct

Question 7

Definition of a digital quantity: does it assume discrete values?  Evaluate the statement: “A digital quantity has a discrete set of values.” Decide whether this captures the essence of digital representation.

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Introduction / Context: Digital versus analog is a core distinction in engineering. A digital quantity is one that assumes values from a countable set, typically finite within a given word length. This item checks your understanding of that definition and its implications for measurement and computation. Given Data / Assumptions: Digital systems represent information with discrete symbols (bits) aggregated into words. A fixed word length implies a finite set of representable codes at any instant. Quantization maps continuous variables to discrete codes. Concept / Approach: By definition, digital quantities are discrete. An n-bit word encodes 2^n possible values (or states). In contrast, analog quantities vary continuously within ranges. The discreteness underpins quantization error, sampling theory, and noise immunity advantages of digital processing. Step-by-Step Solution: Differentiate digital (discrete) from analog (continuous).Relate to word length: n bits → 2^n representable codes.Recognize effects: quantization error and stepwise resolution.Conclude the statement is correct. Verification / Alternative check: Consider a 10-bit ADC: it outputs one of 1024 codes for any input, illustrating discreteness. Why Other Options Are Wrong: Incorrect: Opposes the fundamental definition.Voltage/time/frequency qualifiers: Discreteness applies to the represented variable regardless of domain; sampling in time is also discrete when clocked. Common Pitfalls: Assuming digital waveforms are “square analog” and thus continuous; their representation and interpretation are discrete even if the physical waveform has finite rise time. Final Answer: Correct

Question 8

Ease of information storage with digital techniques: generally easy or not?  Consider modern practice in data storage. Evaluate the statement: “Using digital techniques of information storage is easy.” Determine whether, in general engineering conte…

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Introduction / Context: Digital storage dominates computing because it is practical, scalable, and robust. The statement uses the word “easy,” which we interpret under the Recovery-First policy as “generally simpler and more reliable to implement and manage than analog storage” in mainstream engineering contexts. Given Data / Assumptions: We compare digital storage (flash, magnetic, optical, solid-state) to analog counterparts (magnetic tape with analog tracks, analog film). “Easy” refers to copying, error detection/correction, indexing, random access, and fidelity retention over generations. Modern systems include file systems, redundancy (RAID), and error-correcting codes. Concept / Approach: Digital storage represents information as discrete symbols, enabling perfect copying when error-free and robust recovery with ECC when errors occur. It supports random access, efficient search, compression, and encryption. These features typically make design, use, and maintenance easier than analog media, where noise and generational copying degrade quality continuously. Step-by-Step Solution: Identify key digital advantages: exact duplication, ECC, indexing, metadata.Contrast with analog: cumulative noise, drift, and copy loss.Consider engineering workflows: backups, versioning, and integrity checks are straightforward digitally.Conclude that, broadly, digital storage is easier to use and manage. Verification / Alternative check: Practical evidence: cloud storage, SSDs, and HDDs provide reliable, automated management and integrity features not feasible with analog media at scale. Why Other Options Are Wrong: Incorrect: Ignores the numerous practical advantages of digital storage.Media/capacity qualifiers: The statement is general; benefits extend across technologies and capacities. Common Pitfalls: Overinterpreting “easy” as “trivial.” Engineering still demands careful design (wear leveling, redundancy), but the net difficulty is lower than analog for comparable tasks. Final Answer: Correct

Question 9

OR gate behavior: is output HIGH only when both inputs are HIGH?  Evaluate the statement about a two-input OR gate: “The output is HIGH only when both inputs are HIGH.” Determine whether this accurately describes OR logic.

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Introduction / Context: Recognizing basic gate behavior is essential for reading and designing digital circuits. The statement given resembles the AND gate condition. This item checks whether you can distinguish OR from AND logic based on their truth conditions. Given Data / Assumptions: Standard positive-logic two-input gates. Inputs and output are valid logic levels. No special wiring (e.g., open-collector wired-OR) changes the logical definition. Concept / Approach: The OR operation outputs 1 if at least one input is 1. The only case that yields 0 is when all inputs are 0. The phrase “only when both inputs are HIGH” is the defining condition of an AND gate, not an OR gate. Therefore, the statement about an OR gate is incorrect. Step-by-Step Solution: Recall OR truth table: 0 OR 0 = 0; 1 OR 0 = 1; 0 OR 1 = 1; 1 OR 1 = 1.Compare to the statement: it describes 1 only for input pair (1,1).Note that OR also produces 1 for (1,0) and (0,1), contradicting the given claim.Conclude the statement is incorrect. Verification / Alternative check: Construct with diodes (wired-OR in positive logic) or use a logic simulator; observe that any HIGH input drives the output HIGH. Why Other Options Are Wrong: Correct: Would describe AND, not OR.Wired-OR / XOR distractors: Do not change basic OR truth; XOR is 1 only when inputs differ. Common Pitfalls: Confusing OR with AND because both yield 1 when both inputs are 1; the difference lies in the mixed input cases. Final Answer: Incorrect

Question 10

Digital concepts — Classification: “a microcomputer is not a general-purpose computer.” Decide whether this statement is accurate or inaccurate, considering that many single-chip and personal computers are designed to execute many kinds of programs …

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Introduction / Context: A microcomputer is a computer built around one or more microprocessors. The question asks whether such a machine is “not general-purpose,” which probes the difference between general-purpose and special-purpose computing in digital electronics and computer architecture. Given Data / Assumptions: “General-purpose” means capable of running a wide variety of programs to perform many tasks. Microcomputers include personal computers and single-board computers built on microcontrollers or microprocessors. Embedded systems sometimes use microcomputers but may be configured for a single dedicated task. Concept / Approach: General-purpose vs. special-purpose is about programmability and breadth of tasks, not the physical size or the presence of a microprocessor. If the hardware can execute arbitrary software within its resource limits, it is general-purpose. PCs and SBCs are clear examples. Step-by-Step Solution: Identify definition: general-purpose = runs many types of programs.Map to microcomputers: PCs, laptops, Raspberry Pi boards are microcomputers and clearly general-purpose.Differentiate embedded controllers: some are configured for one task, but the underlying microcomputer is still programmable.Conclude the blanket statement “not general-purpose” is inaccurate. Verification / Alternative check: Consider software variety: operating systems, compilers, and applications run on microcomputers, proving general-purpose capability. Why Other Options Are Wrong: Correct: contradicts the broad programmability of microcomputers.Only true for early 8-bit systems / embedded controllers: many of those also ran multiple programs; the statement is too sweeping.Depends solely on clock speed: capability is not defined by frequency alone. Common Pitfalls: Equating “embedded use” with “special-purpose hardware.” The same microcomputer can be configured either way. Final Answer: Incorrect

Question 11

AND gate behavior — conditional pass-through: For a 2-input AND gate, if one input is fixed HIGH (logic 1), the output value equals the other input's logic level. Classify this statement.

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Introduction / Context: Logic gate identities are foundational. This item checks whether learners recognize that a 2-input AND with one input tied HIGH acts as a buffer (passes the other input unchanged). Given Data / Assumptions: Boolean definition: Y = A * B (AND). One input is fixed at logic 1 (HIGH). Standard positive logic is assumed. Concept / Approach: If Y = A * B and A = 1, then Y = 1 * B = B. The gate becomes a conditional pass-through for B. This is a basic Boolean identity and underlies many enable/disable designs (an AND as an enable gate). Step-by-Step Solution: Start with Y = A * B.Fix A = 1 (HIGH).Compute Y = 1 * B = B.Therefore, the output reflects the other input. Verification / Alternative check: Truth table inspection with A = 1: If B = 0 → Y = 0; if B = 1 → Y = 1. Output equals B in all cases. Why Other Options Are Wrong: Incorrect / negative-logic qualifiers: The identity is true in standard positive logic; NAND or negative logic changes the function.Frequency qualifier: Logical identity is independent of clock rate (assuming proper timing and no hazards). Common Pitfalls: Confusing AND with OR (where tying one input HIGH forces HIGH). Mixing up AND and NAND effects. Final Answer: Correct

Question 12

Waveform measurement — rise time definition: The rise time on the leading edge of a digital pulse is measured from 10% to 90% of its amplitude. Decide whether this definition is accurate.

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Introduction / Context: Rise time is a standard timing parameter for digital and analog step responses. Most instrumentation defines it between 10% and 90% of final amplitude to avoid noise and saturation effects at the extremes. Given Data / Assumptions: A pulse transitions from a low level to a high level. Amplitude is the steady-state difference between final and initial levels. Industry-common definition uses 10%–90% markers; some instruments also support 20%–80% for bandwidth calculations. Concept / Approach: Measuring from 10% to 90% minimizes sensitivity to initial baseline noise and final top-flat saturation. Many bandwidth formulas relate system bandwidth to 10%–90% rise time via empirical constants for simple first-order systems. Step-by-Step Solution: Identify initial level (0%) and final level (100%).Mark the 10% and 90% amplitude points.Measure the interval between those crossings on the leading edge.Report that interval as rise time. Verification / Alternative check: Compare with datasheets: oscilloscopes commonly list rise-time measurement as 10%–90% with an optional 20%–80% mode for specific bandwidth estimation workflows. Why Other Options Are Wrong: 0%–100%: too sensitive to noise and asymptotic behavior.20%–80% “for all scopes”: not universal; 10%–90% is the most common default.“Only valid for analog scopes”: applies equally to modern DSOs. Common Pitfalls: Confusing rise time with propagation delay; measuring on a noisy trace without averaging or proper triggering. Final Answer: Correct

Question 13

Signal world perspective: “The real world is mainly analog.” Assess this statement in the context of sensors, physical phenomena, and data acquisition.

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Introduction / Context: Most physical quantities (temperature, sound, light intensity, position, pressure) vary continuously. Digital electronics sample and quantize these analog phenomena to process and store them efficiently. The statement evaluates this analog predominance. Given Data / Assumptions: Physical signals vary on a continuum. Digital systems require sampling and quantization via ADCs. Sensors (microphones, thermistors, strain gauges) produce analog outputs before digitization. Concept / Approach: Analog describes continuous-time, continuous-amplitude signals. Digital abstracts these into discrete values at discrete times. The pervasiveness of analog sources means digital systems almost always include front-end analog conditioning and conversion stages. Step-by-Step Solution: Identify physical domain: continuous variables dominate.Connect to electronics: sensors output analog voltages/currents.Introduce conversion: ADCs sample/quantize for digital processing.Conclude: the world is mainly analog; digital is a representation. Verification / Alternative check: Observe any data acquisition chain: analog sensor → amplifier/anti-alias filter → ADC → processor. This universal pattern confirms the statement. Why Other Options Are Wrong: Frequency or domain qualifiers (1 kHz, mechanical, acoustics) are arbitrary; analog prevalence is broad across domains. Common Pitfalls: Assuming “digital equals more accurate.” Accuracy depends on the entire chain (noise, bandwidth, resolution), not the mere use of digital representation. Final Answer: Correct

Question 14

Logic voltage levels — overlap question: Is it possible (or desirable) to have an overlap between defined HIGH and LOW input voltage ranges in digital logic families?

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Introduction / Context: Digital logic families specify input thresholds: a maximum recognized LOW (VIL(max)) and a minimum recognized HIGH (VIH(min)). A noise margin is created by leaving a forbidden zone between these ranges. The question asks whether overlap is expected or acceptable. Given Data / Assumptions: Properly designed logic specifies VIL(max) < VIH(min). Noise margins (NMH, NML) rely on that separation. Transient or faulty conditions can momentarily violate these boundaries but are not an intended design feature. Concept / Approach: Overlap would mean some voltages are simultaneously considered valid HIGH and valid LOW, which destroys noise immunity and causes indeterminate behavior. Hence, specifications avoid overlap by definition. There can be an undefined region, but not an intentional overlap of valid ranges. Step-by-Step Solution: Review datasheet thresholds: VIL(max) and VIH(min).Confirm that VIL(max) < VIH(min), leaving a gap.Conclude: no overlap is intended; any observed overlap indicates misuse or out-of-spec operation.Therefore the statement “it is possible to have overlap” is rejected in the design sense. Verification / Alternative check: Check CMOS logic (e.g., 74HC): typical VIL(max) ≈ 0.3VCC and VIH(min) ≈ 0.7VCC, leaving a clear gap for noise margin. Why Other Options Are Wrong: Tristate/open-collector/temperature: these affect drive and bus sharing, not the fundamental requirement to avoid overlap of valid ranges. Common Pitfalls: Confusing undefined regions with overlap; assuming analog noise “makes overlap okay.” It does not—designs must maintain margins. Final Answer: Incorrect

Question 15

Digital systems typically operate with how many stable logical states? Choose the standard count used in binary digital electronics.

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Introduction / Context: Binary digital electronics represent information using discrete logical levels. Understanding the number of fundamental states clarifies why Boolean algebra underpins digital design. Given Data / Assumptions: Binary systems map logic 0 and logic 1 to voltage or current ranges. “Tri-state” or high-impedance refers to outputs, not additional logic values for computation. Noise margins protect the two primary states. Concept / Approach: The standard digital system uses two stable logic states: LOW (0) and HIGH (1). While some devices can present a high-impedance output (for bus sharing), the underlying logic remains binary. Step-by-Step Solution: Identify logic representation: Boolean variables take 0 or 1.Map to physical levels: defined voltage ranges represent each state.Acknowledge tri-state outputs: not a third logic value for computation.Select “two states.” Verification / Alternative check: Boolean algebra, Karnaugh maps, and truth tables are all defined over two logic values, confirming the foundation is binary. Why Other Options Are Wrong: One state: cannot encode information.Three/four states: multi-valued logic exists in research, but mainstream digital hardware is binary. Common Pitfalls: Confusing output tri-state with a third logic level; misinterpreting analog intermediate voltages as valid logic values. Final Answer: two states

Question 16

Oscilloscope basics: The horizontal (X-axis) of a standard oscilloscope display is normally calibrated in units of ________.

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Introduction / Context: Oscilloscopes visualize how electrical quantities vary over time. Recognizing what each axis represents is essential to correctly reading waveforms and timing relationships. Given Data / Assumptions: Standard time-domain operation is assumed (X–Y mode not engaged). Vertical axis displays voltage (or scaled quantity via probes). Horizontal axis advances at a rate set by the timebase/trigger system. Concept / Approach: In normal mode, the timebase sweeps a spot from left to right, mapping elapsed time to horizontal position. Triggering repeatedly stabilizes periodic waveforms on the screen for measurement of period, frequency, duty cycle, and delays. Step-by-Step Solution: Set timebase (e.g., 1 ms/div).Apply a signal and trigger on an edge.Note divisions along X: each division represents the chosen time increment.Measure intervals (period = divisions * time/div). Verification / Alternative check: Consult any oscilloscope front panel: “SEC/DIV” or “TIME/DIV” controls belong to the horizontal system, confirming the unit is time. Why Other Options Are Wrong: Voltage/current/frequency/power: Voltage is vertical in standard mode; current and power require transducers; frequency is derived from the inverse of measured period. Common Pitfalls: Confusing X–Y mode (special case) with normal timebase operation; misreading time/div due to variable persistence or zoom settings. Final Answer: time

Question 17

Counting terminology: When incrementing a binary or decimal count, the digit that changes most frequently from step to step is called the ________.

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Introduction / Context: In digital counting and number representation, different digit positions change at different rates. Knowing which digit changes every increment helps with timing, ripple effects, and understanding binary counters. Given Data / Assumptions: Counting proceeds by +1 increments. Number representation can be binary or decimal; the concept is analogous. Terminology: LSB = least significant bit; MSB = most significant bit. Concept / Approach: The least significant position toggles with every increment. In binary, the LSB flips every count; higher bits change at powers-of-two intervals (every 2 counts for bit1, every 4 counts for bit2, etc.). Thus, the digit that changes most often is the LSB. Step-by-Step Solution: Consider binary sequence …0000, 0001, 0010, 0011, 0100…Track the rightmost bit: it toggles each step.Observe higher bits: they change less frequently.Conclude: the LSB changes most often. Verification / Alternative check: Examine a ripple counter timing diagram; the LSB output has the highest toggle frequency, confirming the definition. Why Other Options Are Wrong: LED/LCD: display technologies, not digit positions.MSB: changes least often in a monotonically increasing count.Parity bit: an error-checking bit, not a position within the magnitude. Common Pitfalls: Confusing digit significance with physical pin position; assuming decimal dynamics differ fundamentally (they do not—the ones place changes every increment). Final Answer: LSB

Question 18

Oscilloscope stability — where to adjust: The front-panel controls that most directly produce a stable, non-moving waveform display are located in the ________ section.

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Introduction / Context: Achieving a stable oscilloscope display is crucial for accurate measurements. While focus, intensity, vertical scale, and timebase all matter, stability primarily depends on triggering controls that synchronize the sweep with the signal. Given Data / Assumptions: Standard time-domain operation. Signal is repetitive or has a feature suitable for trigger. Scope provides trigger level, slope, mode, and source settings. Concept / Approach: Triggering starts each sweep at a consistent point on the waveform (e.g., rising edge crossing a set level). This alignment prevents horizontal drift and creates a steady image. Without proper trigger, even a periodic waveform appears to roll or jitter across the screen. Step-by-Step Solution: Select trigger source (CH1/CH2/External).Choose slope (rising/falling) and coupling (AC/DC).Adjust trigger level to intersect a stable point on the waveform.Set mode (Auto/Normal/Single) for desired behavior. Verification / Alternative check: Switch to free-run (no trigger): the waveform drifts. Re-enable proper trigger: the waveform locks in place, verifying the role of the trigger section. Why Other Options Are Wrong: Vertical section: sets amplitude scale/position, not stability.Horizontal section: sets time scale; without a good trigger, the trace still rolls.Display section/probe port: not responsible for synchronization. Common Pitfalls: Trigger level set beyond waveform peaks; triggering on the wrong source; using AC coupling that filters slow edges. Final Answer: trigger section

Question 19

Square wave characteristics: For an ideal square wave, what is the duty cycle (the percentage of one period that the signal remains HIGH)?

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Introduction / Context: Duty cycle quantifies how long a periodic signal stays in its active (HIGH) state within one full period. For timing, PWM, and digital logic analysis, recognizing duty cycle values is fundamental. Given Data / Assumptions: “Square wave” implies equal HIGH and LOW durations. One period T = time HIGH + time LOW. Duty cycle (%) = (time HIGH / T) * 100. Concept / Approach: An ideal square wave has symmetrical mark and space times. Therefore, time HIGH equals time LOW, each being T/2, yielding a 50% duty cycle. Rectangular waves with unequal durations are not “square” but “pulse” or “rectangular” waves. Step-by-Step Solution: Let time HIGH = T/2 for a square wave.Compute duty cycle = (T/2) / T * 100.Simplify to 50%.Confirm independence from frequency: the ratio holds at any period. Verification / Alternative check: Inspect a symmetric clock signal: the HIGH and LOW occupy equal horizontal spans on the oscilloscope; measurements across divisions confirm 50%. Why Other Options Are Wrong: 10% / 25% / 100% / 0%: represent valid duty cycles for pulses, but they define rectangular waves, not ideal square waves. Common Pitfalls: Calling any periodic pulse “square.” Only the 50% case is strictly square. Be careful with definitions in specifications and timing diagrams. Final Answer: 50%

Question 20

In computer architecture and programming, a set of step-by-step instructions that directs the CPU to perform specific tasks is called a ________.

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Introduction / Context: A fundamental idea in computing is that hardware follows a precise list of instructions to carry out tasks. This ordered list is the essence of software and distinguishes computers from simple hardware-only devices. Understanding the term for this list clarifies how code interacts with the central processing unit (CPU). Given Data / Assumptions: The CPU executes instructions sequentially unless control flow changes. Instructions are written in a programming language and translated to machine code. We are naming the collection of instructions given to a computer. Concept / Approach: The correct term for a set of instructions meant to be executed by a computer is program. A program can be expressed in high-level languages, assembly, or raw machine code. It may include algorithms, data definitions, and control structures that direct the CPU through fetch, decode, and execute cycles. Step-by-Step Solution: Identify what the CPU needs to act: an ordered list of instructions.Recall terminology: such an instruction list is universally called a program.Eliminate distractors not describing executable instruction sets.Conclude the precise term is program. Verification / Alternative check: Operating systems, applications, and firmware are all programs or collections of programs. Compilers transform source programs into executable programs for the target CPU. Why Other Options Are Wrong: instruction manual: human-readable documentation, not CPU-executable instructions. logic unit: typically refers to ALU or control logic, which executes instructions but is not the set of instructions. diagram: a visual representation; again, not executable by the CPU. Common Pitfalls: Confusing a program with a process. A program is the static code; a process is a running instance of that program with resources like memory and open files. Final Answer: program

Digital Concepts Questions