Q: Match microprocessors to typical general-purpose register widths: (A) Intel 8085, (B) Intel 8086, (C) Motorola 68000.

Introduction / Context: Register width determines native data handling and influences instruction set design. This question links three foundational CPUs to the bit-width of their general-purpose registers commonly cited in textbooks and exams. Given Data / Assumptions: 8085: 8-bit accumulator and general-purpose registers (with 16-bit register pairs for addressing/arithmetic). 8086: 16-bit general-purpose registers (AX, BX, CX, DX, etc.). 68000: 32-bit data and address registers internally (despite a 16-bit external data bus). Concept / Approach: Use the canonical teaching mapping: 8085 → 8-bit (often referenced as 8/16 because of register pairs), 8086 → 16-bit, 68000 → 32-bit registers. The option set encodes 8085 as 8/16 to reflect pair usage. Step-by-Step Solution: A (8085) → 8-bit registers (with 16-bit pairs) → choose 8/16 → 3.B (8086) → 16-bit → 2.C (68000) → 32-bit → 1. Verification / Alternative check: Manuals: 8085 has 8-bit A, B, C, D, E, H, L; 8086 has 16-bit AX..DX; 68000 provides D0–D7 and A0–A7 as 32-bit registers internally. Why Other Options Are Wrong: A-1, B-2, C-3: Assigns 32-bit to 8085 erroneously. A-2, B-3, C-1: Swaps 8085 and 8086 widths. A-3, B-1, C-2: Assigns 32-bit to 8086 and 16-bit to 68000—incorrect. Common Pitfalls: Confusing bus width with register width (68000’s 16-bit bus vs 32-bit registers). Forgetting 8085’s register-pair operations (BC, DE, HL) do not make it a native 16-bit CPU. Final Answer: A-3, B-2, C-1

Q: Match circuit types to key small-signal characteristics: (A) Darlington pair, (B) Common-Base (CB) amplifier, (C) Cascade amplifier (multi-stage) — identify the best mapping among voltage gain, input impedance, and high-frequency isolation.

Introduction / Context: Small-signal amplifier topologies are characterized by input/output impedance, voltage gain, and frequency behavior. This question distinguishes between the Darlington emitter follower, CB stage, and cascaded multi-stage amplifiers often seen in RF front ends and audio preamps. Given Data / Assumptions: Darlington pair behaves like a high-gain emitter follower. Common-Base amplifiers show low input impedance and good high-frequency isolation. Cascade (multi-stage) connection can deliver high overall voltage gain. Concept / Approach: Match each topology to its hallmark: Darlington → very high input impedance and voltage gain near 1; CB → low input impedance, useful for wideband/high-frequency stages; cascade → stacking stages multiplies voltage gain. Step-by-Step Solution: A (Darlington) → two transistors as an emitter follower → voltage gain ≈ 1 with very high input impedance → 2.B (CB amplifier) → emitter is input, base common → low input impedance and good HF isolation → 3.C (Cascade amplifier) → multiple gain stages → high overall voltage gain → 1. Verification / Alternative check: Emitter follower’s Av ~ 0.9–0.99; CB stage’s Rin ~ tens of ohms and wide bandwidth; cascading two CE stages yields Av ≫ 1. These align with the selected descriptors. Why Other Options Are Wrong: A-1, B-2, C-3: Misattributes large voltage gain to Darlington and high input impedance to CB. A-2, B-1, C-3: Gives high gain to CB and isolation to cascade—reversed. A-3, B-1, C-2: Swaps multiple properties simultaneously. Common Pitfalls: Assuming Darlington provides large voltage gain; it primarily boosts current gain and input impedance. Confusing cascade (multi-stage) with cascode (CE–CB pair). Cascode has different properties. Final Answer: A-2, B-3, C-1

Q: Match the amplifier types to their characteristic frequency responses: (A) RC-coupled amplifier, (B) Tuned amplifier, (C) Chopper-stabilized amplifier, (D) DC amplifier — with: (1) Very low drift, (2) Flat response from 0 Hz onward, (3) Flat respons…

Introduction / Context: Different amplifier configurations serve different spectral needs. Recognizing how their frequency responses look (flat band, cutoffs, resonance, drift performance) is crucial for audio, RF, and precision DC applications. This question pairs four common amplifier classes with their signature frequency-response traits. Given Data / Assumptions: (A) RC-coupled amplifier (B) Tuned amplifier (C) Chopper-stabilized amplifier (D) DC amplifier Candidate traits: (1) very low drift, (2) flat from 0 Hz, (3) flat with finite passband and cutoffs, (4) resonant peak Concept / Approach: RC-coupled stages (e.g., common-emitter with coupling/bypass capacitors) exhibit a mid-band region of nearly flat gain bounded by low- and high-frequency cutoffs. Tuned amplifiers include frequency-selective LC tanks, giving a peaked response at resonance (high Q → narrowband). Chopper-stabilized amplifiers up-convert DC/low-frequency signals, amplify, and demodulate to achieve ultra-low offset and drift. True DC amplifiers pass down to 0 Hz (no coupling caps), so their passband includes DC. Step-by-Step Solution: A → (3): RC coupling → flat midband with fL and fH cutoffs.B → (4): Tuned → resonant/gain peak at center frequency.C → (1): Chopper-stabilized → very low offset/drift.D → (2): DC amplifier → extends to 0 Hz. Verification / Alternative check: Bode plots and standard small-signal models confirm these shapes: single-pole high/low-cutoff for RC, band-pass with resonance for tuned LC, and flat-to-DC for DC amplifiers. Why Other Options Are Wrong: Swapping (2) and (3) mixes DC capability with AC-coupled behavior; assigning (4) to RC ignores the absence of a tuned tank. Common Pitfalls: Assuming “flat” always means DC-to-∞; forgetting that coupling capacitors exclude 0 Hz; conflating chopper stabilization with simple auto-zeroing without drift benefits. Final Answer: A-3, B-4, C-1, D-2

Q: Match signals to their typical types: (A) Output of a signal generator, (B) Error signal from a synchro, (C) Output of a JK flip-flop, (D) Signal received by radar — with: (1) Modulated, (2) Digital, (3) Analog, (4) Stochastic (random).

Introduction / Context: Engineering signals are broadly categorized by structure and randomness: analog vs digital, modulated vs baseband, and deterministic vs stochastic. This question matches common sources to their most representative signal type. Given Data / Assumptions: (A) Signal generator output (B) Synchro error signal (C) JK flip-flop output (D) Radar-received signal Types: (1) modulated, (2) digital, (3) analog, (4) stochastic Concept / Approach: Laboratory/RF signal generators commonly produce modulated outputs (AM/FM/PM, pulse) in addition to pure tones, so “modulated” captures the general case. Synchros are electromechanical transducers; their error signals are continuous voltages proportional to angular misalignment → analog. A JK flip-flop is a bistable digital device with logic-level output waveforms. Radar returns are random due to thermal noise, clutter, and target fluctuations → stochastic. Step-by-Step Solution: A → (1): Signal generators often output AM/FM/PM or pulse-modulated signals.B → (3): Synchro error voltages vary continuously with angle.C → (2): JK flip-flop yields discrete logic levels and state transitions.D → (4): Received radar signals include noise/clutter, modeled statistically. Verification / Alternative check: Datasheets for modern function/RF generators list modulation features; synchro theory defines analog differential voltages; digital logic families define flip-flop outputs; radar detection uses probabilistic models (Swerling, CFAR) grounded in stochastic processes. Why Other Options Are Wrong: Labeling the synchro error as modulated misstates its role; calling flip-flop outputs analog contradicts digital operation; radar signals are not purely deterministic. Common Pitfalls: Assuming “signal generator” always means a simple sine source; ignoring noise dominance in received RF signals. Final Answer: A-1, B-3, C-2, D-4

Q: Match digital building blocks to their typical functions: (A) Shift register, (B) Counter, (C) Decoder — with: (1) Frequency division, (2) Addressing in memory chips, (3) Serial-to-parallel data conversion.

Introduction / Context: Basic digital modules recur across systems, each solving a canonical task. Recognizing their “textbook” roles helps you design datapaths and control logic efficiently. Given Data / Assumptions: (A) Shift register (B) Counter (C) Decoder Functions: (1) frequency division, (2) memory addressing/line selection, (3) serial-to-parallel conversion Concept / Approach: Shift registers reorder bits in time and space; with appropriate taps they convert serial streams to parallel words. Counters advance through states on clock edges; the rollover pattern divides the input clock frequency by an integer. Decoders map n input lines to 2^n mutually exclusive outputs, widely used to select memory rows/columns or I/O devices. Step-by-Step Solution: A → (3): Shift register (e.g., SIPO) converts serial input to parallel output.B → (1): A binary counter divides frequency (e.g., modulo-N division).C → (2): Decoders enable one-of-many line selection in memory chips. Verification / Alternative check: 74xx/40xx families: 74HC595 (shift), 74HC4040 (counter), 74HC138 (decoder) align with these roles; timing diagrams confirm behavior. Why Other Options Are Wrong: Swapping decoder and counter confuses selection logic with time-sequence counting; assigning serial-to-parallel to counters misstates function. Common Pitfalls: Overlooking that shift registers can also perform parallel-to-serial (PISO) and simple delay; assuming all frequency division requires PLLs (counters suffice for integer division). Final Answer: A-3, B-1, C-2

Question 1

Match radio/ionospheric terms to their definitions: (A) Penetration frequency, (B) Optimum working frequency (OWF), (C) Gyro-frequency, (D) Maximum usable frequency (MUF).

Accepted Answer

Introduction / Context: This question checks foundational knowledge in ionospheric radio propagation. You must distinguish among penetration frequency, optimum working frequency (OWF), gyro-frequency, and maximum usable frequency (MUF)—terms that determine whether, and how well, radio waves traverse or are refracted by the ionosphere. Given Data / Assumptions: Penetration frequency: associated with the critical frequency concept. OWF: frequency that gives the most reliable ionospheric link. Gyro-frequency: electron gyration in a magnetic field. MUF: the highest frequency that returns to Earth for a given path and conditions. Concept / Approach: Map each term to classic textbook definitions used in shortwave/skywave communication: MUF sets the upper bound for refraction; OWF is a practical sweet spot below MUF; gyro-frequency depends on the geomagnetic field; penetration frequency is tied to the critical frequency beyond which a wave penetrates instead of reflecting in vertical incidence. Step-by-Step Solution: A (Penetration frequency) → same idea as critical frequency for vertical incidence → 2.B (OWF) → most effective frequency for stable ionospheric links → 4.C (Gyro-frequency) → lowest gyration frequency of charged particles in a fixed magnetic field → 1.D (MUF) → highest usable frequency for a given path and time → 3. Verification / Alternative check: Operational practice: HF operators choose OWF ≈ 0.85 * MUF to balance reliability and fading; gyro-frequency is orders of magnitude below HF in the ionosphere; critical/penetration frequency determines whether vertical rays pass through. Why Other Options Are Wrong: A-4, B-1, C-3, D-2: Confuses path limits and magnetic phenomena. A-1, B-3, C-2, D-4: Swaps MUF and OWF; misstates gyro/critical relations. Common Pitfalls: Using MUF directly as the operating frequency; links are more stable a bit below MUF. Confusing critical (vertical) with oblique incidence behavior. Final Answer: A-2, B-4, C-1, D-3

Question 2

Match electronic components to predominant noise types: (A) Resistance, (B) Diode, (C) Triode, (D) p–n junction — with: (1) current noise, (2) partition noise, (3) shot noise, (4) atmospheric noise, (5) Johnson (thermal) noise.

Accepted Answer

Introduction / Context: Recognizing dominant noise mechanisms is key for low-noise design. Thermal agitation in resistors, discrete charge flow in junctions, and carrier partition in multi-electrode devices create distinct spectral behaviors that affect receivers and amplifiers across RF and audio bands. Given Data / Assumptions: Resistor noise is thermal (Johnson noise). Diode junctions exhibit shot noise due to discrete charge carriers traversing a barrier. Vacuum triodes exhibit partition noise from electron stream division among electrodes. p–n junctions can exhibit current-related (shot/flicker) noise; here 'current noise' is the remaining classified term to pair. Concept / Approach: Map each device to the noise it is most classically associated with in exam syllabi: Johnson noise ↔ resistors; shot noise ↔ diodes; partition noise ↔ multi-electrode tubes; current noise ↔ semiconductor junction conduction fluctuations. Step-by-Step Solution: A (Resistance) → Johnson (thermal) noise → 5.B (Diode) → shot noise from discrete charge arrivals → 3.C (Triode) → partition noise in electron stream → 2.D (p–n junction) → categorized here as current noise → 1. Verification / Alternative check: Spectral traits: thermal noise ~ kTB across resistors; shot noise current ~ 2qI*B in junctions; partition noise arises where carriers split among paths (e.g., triodes). Why Other Options Are Wrong: A-1, B-2, C-3, D-5: Misplaces thermal and shot noise pairings. A-3, B-5, C-1, D-2: Assigns shot noise to resistors, which is incorrect. A-3, B-5, C-2, D-1: Gives diodes thermal noise as dominant, which is not typical. Common Pitfalls: Confusing thermal noise (present in any resistance) with shot noise (junctions). Assuming atmospheric noise originates in components; it is an external interference source. Final Answer: A-5, B-3, C-2, D-1

Question 3

Match instruments to the principal quantity they measure: (A) Hot-wire instrument, (B) PMMC instrument, (C) Electrostatic voltmeter, (D) Lock-in amplifier.

Accepted Answer

Introduction / Context: Measurement systems often hinge on choosing an instrument that matches the signal characteristic: RMS value, DC-only measurement, very high impedance voltage sensing, or phase-sensitive detection. This mapping reinforces key associations used in labs and exams. Given Data / Assumptions: Hot-wire instruments respond to heating, hence read true RMS. PMMC (Permanent Magnet Moving Coil) instruments respond to DC values. Electrostatic voltmeters sense electrostatic force and measure voltage only. Lock-in amplifiers use phase-sensitive detection to measure signals buried in noise and report amplitude/phase relative to a reference. Concept / Approach: Use the defining physical principle of each instrument to match to the measured quantity. Step-by-Step Solution: A (Hot-wire) → heating ∝ I^2 → true RMS value → 3.B (PMMC) → rectified inputs require external circuits; intrinsic movement measures DC → 4.C (Electrostatic) → force between plates ∝ V^2; measures only voltage → 1.D (Lock-in) → phase-sensitive detector yields amplitude and phase → 2. Verification / Alternative check: In AC measurement, hot-wire meters read correctly regardless of waveform due to thermal response; PMMC requires rectifiers for AC and then indicates average/DC equivalent; electrostatic devices are preferred for high-voltage, high-impedance measurements; lock-ins extract narrowband components at the reference frequency and phase. Why Other Options Are Wrong: A-1, B-4, C-2, D-3: Hot-wire does not measure voltage-only; lock-in is not strictly RMS meter. A-3, B-2, C-1, D-4: Misassigns PMMC and lock-in functions. A-2, B-3, C-4, D-1: Interchanges multiple roles. Common Pitfalls: Assuming PMMC reads AC without rectification. Confusing RMS indication with average-responding meters. Final Answer: A-3, B-4, C-1, D-2

Question 4

Match DOS command names to their primary purposes: (A) DBLSPACE, (B) MEM, (C) SYS, (D) DELTREE — choose the correct mapping for disk compression, memory display, DOS system transfer, and recursive directory deletion.

Accepted Answer

Introduction / Context: Legacy DOS commands still appear in certification exams and interviews because they illustrate core OS concepts: storage, memory, bootstrapping, and file-system operations. Correctly mapping these commands helps solidify command-line literacy. Given Data / Assumptions: DBLSPACE: double-space compression utility for drives/files. MEM: reports used/free memory. SYS: transfers DOS system files to a disk (makes it bootable). DELTREE: deletes a directory and its subdirectories recursively. Concept / Approach: Recall canonical DOS usage: DBLSPACE /DRVSPACE for compression; MEM /C /P for memory; SYS A: to make a system disk; DELTREE C:\TEMP to remove a tree. Step-by-Step Solution: A (DBLSPACE) → compresses files to increase capacity → 4.B (MEM) → displays memory usage → 2.C (SYS) → copies system files to target disk → 3.D (DELTREE) → deletes directory trees → 1. Verification / Alternative check: Help outputs (e.g., 'MEM /?' or DOS manuals) corroborate each mapping and the typical switches used with each utility. Why Other Options Are Wrong: A-4, B-3, C-2, D-1: Swaps MEM and SYS roles. A-2, B-3, C-4, D-1: Assigns compression to MEM; incorrect. A-1, B-2, C-3, D-4: Misplaces DBLSPACE and DELTREE functions. Common Pitfalls: Confusing DBLSPACE (older) with DRVSPACE (later). Forgetting that DELTREE is dangerous and permanent. Final Answer: A-4, B-2, C-3, D-1

Question 5

Match transmission structures to their typical propagation modes: (A) Stripline, (B) Hollow rectangular waveguide, (C) Microstrip, (D) Corrugated waveguide.

Accepted Answer

Introduction / Context: Microwave structures support different field configurations. Recognizing whether a line supports pure TEM, quasi-TEM, TE/TM, or hybrid modes is crucial for impedance control, dispersion, and loss calculations in RF design. Given Data / Assumptions: Stripline: homogeneous dielectric environment between ground planes. Hollow rectangular waveguide: air-filled metallic duct. Microstrip: inhomogeneous (air + substrate) planar line. Corrugated waveguide: ridged/corrugated interior for mode control (e.g., HE11). Concept / Approach: Pure TEM requires a simply connected, homogeneous medium (stripline). In hollow waveguides, true TEM cannot propagate; instead, TE/TM modes exist. Microstrip supports quasi-TEM due to field fringing into air. Corrugations create hybrid modes with desirable dispersion and low cross-polarization. Step-by-Step Solution: A (Stripline) → pure TEM → 2.B (Rectangular waveguide) → TE/TM modes (no TEM) → 3.C (Microstrip) → quasi-TEM (hybrid E/H) → 1.D (Corrugated waveguide) → hybrid modes (e.g., HE11) → 4. Verification / Alternative check: Field solutions show microstrip's effective dielectric constant < substrate permittivity because some energy is in air; rectangular guides have cut-off for dominant TE10; stripline’s symmetry supports TEM at all frequencies until dispersion from dielectric losses/width becomes relevant. Why Other Options Are Wrong: A-2, B-1, C-3, D-4: Claims waveguide supports quasi-TEM—incorrect. A-4, B-1, C-3, D-2: Misplaces hybrid/quasi-TEM assignments. A-4, B-3, C-1, D-2: Assigns hybrid to stripline and microstrip to TE/TM. Common Pitfalls: Assuming microstrip is pure TEM; it is only quasi-TEM. Forgetting that hollow metallic waveguides cannot support TEM without a center conductor. Final Answer: A-2, B-3, C-1, D-4

Question 6

Match microprocessors to typical general-purpose register widths: (A) Intel 8085, (B) Intel 8086, (C) Motorola 68000.

Accepted Answer

Introduction / Context: Register width determines native data handling and influences instruction set design. This question links three foundational CPUs to the bit-width of their general-purpose registers commonly cited in textbooks and exams. Given Data / Assumptions: 8085: 8-bit accumulator and general-purpose registers (with 16-bit register pairs for addressing/arithmetic). 8086: 16-bit general-purpose registers (AX, BX, CX, DX, etc.). 68000: 32-bit data and address registers internally (despite a 16-bit external data bus). Concept / Approach: Use the canonical teaching mapping: 8085 → 8-bit (often referenced as 8/16 because of register pairs), 8086 → 16-bit, 68000 → 32-bit registers. The option set encodes 8085 as 8/16 to reflect pair usage. Step-by-Step Solution: A (8085) → 8-bit registers (with 16-bit pairs) → choose 8/16 → 3.B (8086) → 16-bit → 2.C (68000) → 32-bit → 1. Verification / Alternative check: Manuals: 8085 has 8-bit A, B, C, D, E, H, L; 8086 has 16-bit AX..DX; 68000 provides D0–D7 and A0–A7 as 32-bit registers internally. Why Other Options Are Wrong: A-1, B-2, C-3: Assigns 32-bit to 8085 erroneously. A-2, B-3, C-1: Swaps 8085 and 8086 widths. A-3, B-1, C-2: Assigns 32-bit to 8086 and 16-bit to 68000—incorrect. Common Pitfalls: Confusing bus width with register width (68000’s 16-bit bus vs 32-bit registers). Forgetting 8085’s register-pair operations (BC, DE, HL) do not make it a native 16-bit CPU. Final Answer: A-3, B-2, C-1

Question 7

Match circuit types to key small-signal characteristics: (A) Darlington pair, (B) Common-Base (CB) amplifier, (C) Cascade amplifier (multi-stage) — identify the best mapping among voltage gain, input impedance, and high-frequency isolation.

Accepted Answer

Introduction / Context: Small-signal amplifier topologies are characterized by input/output impedance, voltage gain, and frequency behavior. This question distinguishes between the Darlington emitter follower, CB stage, and cascaded multi-stage amplifiers often seen in RF front ends and audio preamps. Given Data / Assumptions: Darlington pair behaves like a high-gain emitter follower. Common-Base amplifiers show low input impedance and good high-frequency isolation. Cascade (multi-stage) connection can deliver high overall voltage gain. Concept / Approach: Match each topology to its hallmark: Darlington → very high input impedance and voltage gain near 1; CB → low input impedance, useful for wideband/high-frequency stages; cascade → stacking stages multiplies voltage gain. Step-by-Step Solution: A (Darlington) → two transistors as an emitter follower → voltage gain ≈ 1 with very high input impedance → 2.B (CB amplifier) → emitter is input, base common → low input impedance and good HF isolation → 3.C (Cascade amplifier) → multiple gain stages → high overall voltage gain → 1. Verification / Alternative check: Emitter follower’s Av ~ 0.9–0.99; CB stage’s Rin ~ tens of ohms and wide bandwidth; cascading two CE stages yields Av ≫ 1. These align with the selected descriptors. Why Other Options Are Wrong: A-1, B-2, C-3: Misattributes large voltage gain to Darlington and high input impedance to CB. A-2, B-1, C-3: Gives high gain to CB and isolation to cascade—reversed. A-3, B-1, C-2: Swaps multiple properties simultaneously. Common Pitfalls: Assuming Darlington provides large voltage gain; it primarily boosts current gain and input impedance. Confusing cascade (multi-stage) with cascode (CE–CB pair). Cascode has different properties. Final Answer: A-2, B-3, C-1

Question 8

Match the items in communication systems: (A) Ring modulator, (B) VCO (Voltage-Controlled Oscillator), (C) Foster–Seeley discriminator, (D) Mixer — with their primary functions: (1) Clock recovery, (2) Demodulation of FM, (3) Frequency conversion, (…

Accepted Answer

Introduction / Context: Communication systems rely on distinct building blocks, each serving a well-defined role in modulation, demodulation, frequency translation, or timing. This matching exercise checks whether you can associate common RF/communication components with their hallmark functions: ring modulators for suppressed-carrier generation, VCOs for frequency generation/modulation, Foster–Seeley discriminators for FM demodulation, and mixers for heterodyning (frequency conversion). Given Data / Assumptions: (A) Ring modulator (B) VCO (Voltage-Controlled Oscillator) (C) Foster–Seeley discriminator (D) Mixer Possible roles: (1) clock recovery, (2) FM demodulation, (3) frequency conversion, (4) summing, (5) FM generation, (6) DSB-SC generation Concept / Approach: A ring modulator (a balanced modulator) multiplies two signals and cancels the carrier, producing a double-sideband suppressed-carrier (DSB-SC) output. A VCO produces a frequency proportional to a control voltage; by driving that control line with the modulating signal, it generates frequency modulation (FM). The Foster–Seeley discriminator is a classic frequency-to-voltage detector used for narrowband FM demodulation. A mixer multiplies two sinusoids, producing sum and difference frequencies, enabling up/down conversion in superheterodyne receivers and transmitters. Step-by-Step Solution: Step 1: Ring modulator → DSB-SC generation: choose (6).Step 2: VCO → FM generation: choose (5).Step 3: Foster–Seeley discriminator → FM demodulation: choose (2).Step 4: Mixer → frequency conversion (heterodyning): choose (3). Verification / Alternative check: Textbook transmitter chains: balanced modulator for DSB-SC, optional carrier reinsertion for AM; FM transmitters employ VCOs or indirect modulation loops. Receiver IF strips commonly use Foster–Seeley (or ratio detectors) for FM detection. Mixers are ubiquitous in front ends (RF→IF) and in transmit chains (IF→RF). Why Other Options Are Wrong: (1) Clock recovery is typically a role of PLLs/CR circuits, not ring modulators or mixers directly. (4) Simple summing is performed by adders/combiners, not ring modulators. Swapping VCO and discriminator confuses generation with detection. Common Pitfalls: Assuming any multiplier equals a “mixer” in all contexts; forgetting that balanced modulators suppress the carrier; confusing PLL-based FM synthesis with the discriminator’s detection role. Final Answer: A-6, B-5, C-2, D-3

Question 9

Match the amplifier types to their characteristic frequency responses: (A) RC-coupled amplifier, (B) Tuned amplifier, (C) Chopper-stabilized amplifier, (D) DC amplifier — with: (1) Very low drift, (2) Flat response from 0 Hz onward, (3) Flat respons…

Accepted Answer

Introduction / Context: Different amplifier configurations serve different spectral needs. Recognizing how their frequency responses look (flat band, cutoffs, resonance, drift performance) is crucial for audio, RF, and precision DC applications. This question pairs four common amplifier classes with their signature frequency-response traits. Given Data / Assumptions: (A) RC-coupled amplifier (B) Tuned amplifier (C) Chopper-stabilized amplifier (D) DC amplifier Candidate traits: (1) very low drift, (2) flat from 0 Hz, (3) flat with finite passband and cutoffs, (4) resonant peak Concept / Approach: RC-coupled stages (e.g., common-emitter with coupling/bypass capacitors) exhibit a mid-band region of nearly flat gain bounded by low- and high-frequency cutoffs. Tuned amplifiers include frequency-selective LC tanks, giving a peaked response at resonance (high Q → narrowband). Chopper-stabilized amplifiers up-convert DC/low-frequency signals, amplify, and demodulate to achieve ultra-low offset and drift. True DC amplifiers pass down to 0 Hz (no coupling caps), so their passband includes DC. Step-by-Step Solution: A → (3): RC coupling → flat midband with fL and fH cutoffs.B → (4): Tuned → resonant/gain peak at center frequency.C → (1): Chopper-stabilized → very low offset/drift.D → (2): DC amplifier → extends to 0 Hz. Verification / Alternative check: Bode plots and standard small-signal models confirm these shapes: single-pole high/low-cutoff for RC, band-pass with resonance for tuned LC, and flat-to-DC for DC amplifiers. Why Other Options Are Wrong: Swapping (2) and (3) mixes DC capability with AC-coupled behavior; assigning (4) to RC ignores the absence of a tuned tank. Common Pitfalls: Assuming “flat” always means DC-to-∞; forgetting that coupling capacitors exclude 0 Hz; conflating chopper stabilization with simple auto-zeroing without drift benefits. Final Answer: A-3, B-4, C-1, D-2

Question 10

Match C operators with their precedence (1 = highest, 4 = lowest): (A) ! (logical NOT), (B) < and > (relational), (C) * (multiplication), (D) = (assignment).

Accepted Answer

Introduction / Context: Operator precedence in C determines how expressions are grouped without parentheses. Misunderstanding precedence leads to subtle logic errors. This item maps four widely used operators to an ordered precedence scale (1 = highest, 4 = lowest) consistent with standard C rules. Given Data / Assumptions: (A) ! (unary logical NOT) (B) < and > (relational operators) (C) * (multiplication) (D) = (assignment) Scale: 1 highest priority … 4 lowest priority Concept / Approach: In C, unary operators (like !) bind tighter than multiplicative operators. Multiplicative operators (*, /, %) bind tighter than additive, relational, equality, logical, and assignment operators. Relational operators (<, >, <=, >=) have lower precedence than multiplicative but higher than assignment. The assignment operator = has among the lowest precedence. Step-by-Step Solution: Assign ! → precedence 1 (highest among the set).Assign * → precedence 2 (multiplicative tier).Assign <,> → precedence 3 (relational tier).Assign = → precedence 4 (assignment, very low). Verification / Alternative check: Check expression: a = b < c * d parses as a = (b < (c * d)), confirming * precedes relational, and relational precedes assignment; similarly !x * y parses as (!x) * y. Why Other Options Are Wrong: Any mapping that places relational above multiplicative or assignment above relational contradicts the C precedence table; placing ! below * is also incorrect. Common Pitfalls: Confusing precedence with associativity; assuming logical operators always evaluate last (only assignment is lower among this set). Final Answer: A-1, B-3, C-2, D-4

Question 11

Match signals to their typical types: (A) Output of a signal generator, (B) Error signal from a synchro, (C) Output of a JK flip-flop, (D) Signal received by radar — with: (1) Modulated, (2) Digital, (3) Analog, (4) Stochastic (random).

Accepted Answer

Introduction / Context: Engineering signals are broadly categorized by structure and randomness: analog vs digital, modulated vs baseband, and deterministic vs stochastic. This question matches common sources to their most representative signal type. Given Data / Assumptions: (A) Signal generator output (B) Synchro error signal (C) JK flip-flop output (D) Radar-received signal Types: (1) modulated, (2) digital, (3) analog, (4) stochastic Concept / Approach: Laboratory/RF signal generators commonly produce modulated outputs (AM/FM/PM, pulse) in addition to pure tones, so “modulated” captures the general case. Synchros are electromechanical transducers; their error signals are continuous voltages proportional to angular misalignment → analog. A JK flip-flop is a bistable digital device with logic-level output waveforms. Radar returns are random due to thermal noise, clutter, and target fluctuations → stochastic. Step-by-Step Solution: A → (1): Signal generators often output AM/FM/PM or pulse-modulated signals.B → (3): Synchro error voltages vary continuously with angle.C → (2): JK flip-flop yields discrete logic levels and state transitions.D → (4): Received radar signals include noise/clutter, modeled statistically. Verification / Alternative check: Datasheets for modern function/RF generators list modulation features; synchro theory defines analog differential voltages; digital logic families define flip-flop outputs; radar detection uses probabilistic models (Swerling, CFAR) grounded in stochastic processes. Why Other Options Are Wrong: Labeling the synchro error as modulated misstates its role; calling flip-flop outputs analog contradicts digital operation; radar signals are not purely deterministic. Common Pitfalls: Assuming “signal generator” always means a simple sine source; ignoring noise dominance in received RF signals. Final Answer: A-1, B-3, C-2, D-4

Question 12

Match digital building blocks to their typical functions: (A) Shift register, (B) Counter, (C) Decoder — with: (1) Frequency division, (2) Addressing in memory chips, (3) Serial-to-parallel data conversion.

Accepted Answer

Introduction / Context: Basic digital modules recur across systems, each solving a canonical task. Recognizing their “textbook” roles helps you design datapaths and control logic efficiently. Given Data / Assumptions: (A) Shift register (B) Counter (C) Decoder Functions: (1) frequency division, (2) memory addressing/line selection, (3) serial-to-parallel conversion Concept / Approach: Shift registers reorder bits in time and space; with appropriate taps they convert serial streams to parallel words. Counters advance through states on clock edges; the rollover pattern divides the input clock frequency by an integer. Decoders map n input lines to 2^n mutually exclusive outputs, widely used to select memory rows/columns or I/O devices. Step-by-Step Solution: A → (3): Shift register (e.g., SIPO) converts serial input to parallel output.B → (1): A binary counter divides frequency (e.g., modulo-N division).C → (2): Decoders enable one-of-many line selection in memory chips. Verification / Alternative check: 74xx/40xx families: 74HC595 (shift), 74HC4040 (counter), 74HC138 (decoder) align with these roles; timing diagrams confirm behavior. Why Other Options Are Wrong: Swapping decoder and counter confuses selection logic with time-sequence counting; assigning serial-to-parallel to counters misstates function. Common Pitfalls: Overlooking that shift registers can also perform parallel-to-serial (PISO) and simple delay; assuming all frequency division requires PLLs (counters suffice for integer division). Final Answer: A-3, B-1, C-2

Question 13

Match common computing terms to their meanings: (A) Word wrap, (B) Client, (C) Multitasking, (D) Landscape — with: (1) Interleaved execution of two or more programs, (2) Automatically moves a long word to the next line, (3) An application receiving …

Accepted Answer

Introduction / Context: User-interface and OS terminology is ubiquitous across software. This question ensures you can map everyday computing terms to their precise definitions in word processing, networking, and operating systems. Given Data / Assumptions: (A) Word wrap (B) Client (C) Multitasking (D) Landscape Definitions: (1) interleaved execution of programs, (2) auto move a word to next line, (3) application receiving service/data, (4) page orientation Concept / Approach: Word wrap is a document editor feature that prevents words from being split or clipped at the line end. A client is the consumer in client-server architecture (e.g., a browser). Multitasking is the OS capability to interleave or schedule multiple tasks on a CPU. Landscape refers to horizontal page orientation (wider than tall) used for worksheets, slides, and wide tables. Step-by-Step Solution: Map word wrap → (2).Map client → (3).Map multitasking → (1).Map landscape → (4). Verification / Alternative check: Most editors expose “Word wrap” in view/preferences; OS textbooks define multitasking; networking texts define client vs server; page setup dialogs show Landscape/Portrait options. Why Other Options Are Wrong: Mixing client with server roles; confusing page orientation with print scaling; treating word wrap as hyphenation. Common Pitfalls: Assuming multitasking implies parallelism (true only with multi-core; otherwise, it is time-sharing); thinking word wrap inserts hard line breaks (it does not). Final Answer: A-2, B-3, C-1, D-4

Question 14

Match Microsoft Word commands/UI elements to their meanings: (A) END, (B) HOME, (C) Status bar — with: (1) Shows current cursor/section position, (2) Move cursor to beginning of current line, (3) Move cursor to end of document.

Accepted Answer

Introduction / Context: Efficient document navigation depends on knowing keyboard commands and UI indicators. This question pairs common Word actions (END, HOME) and the Status bar with their typical behaviors. Given Data / Assumptions: END key behavior in Word HOME key behavior in Word Status bar contents Concept / Approach: In Word, END usually moves the caret to the end of the current line, but in navigation contexts and many editors, END/HOME also relate to document extremities. The intent of this classic MCQ set is to associate END with moving to the end (here, of the document), HOME with beginning of line, and the Status bar as the on-screen element that reports cursor position, page count, language, and other states. Step-by-Step Solution: A → (3): END → move to end of document (by this item’s convention).B → (2): HOME → move to beginning of current line.C → (1): Status bar → displays position/info. Verification / Alternative check: Word’s status bar shows Page x of y, Section, Ln/Col, etc.; keyboard shortcuts tables document HOME/END behaviors (with Ctrl variants for line vs document). Why Other Options Are Wrong: Swapping HOME/END roles or treating the Status bar as a command key is incorrect. Common Pitfalls: Forgetting Ctrl+HOME (document start) vs HOME (line start), Ctrl+END (document end) vs END (line end). Editors differ slightly; this question follows a common MCQ convention. Final Answer: A-3, B-2, C-1

Question 15

Match classic network synthesis concepts to their originators/definitions: (A) Reactance theorem, (B) Driving-point impedance, (C) Continued-fraction expansion, (D) Bisection theorem — with: (1) Foster, (2) Bartlett, (3) Cauer, (4) Positive-real fun…

Accepted Answer

Introduction / Context: Classical network synthesis links mathematical properties of impedances/admittances to realizable passive networks. This question ties four famous results/names to their associated concepts. Given Data / Assumptions: Reactance theorem Driving-point impedance Continued-fraction expansion Bisection theorem Names/definitions: Foster, Bartlett, Cauer, positive-real (PR) function Concept / Approach: Foster’s reactance theorem characterizes reactance vs frequency for lossless networks, underlying Foster canonical forms. A driving-point impedance function suitable for passive realization must be positive-real (PR). Cauer’s method uses continued-fraction expansion to realize networks (Cauer I/II forms). Bartlett’s bisection theorem aids in symmetrical network design by splitting networks while preserving properties. Step-by-Step Solution: A → (1): Reactance theorem ↔ Foster.B → (4): Driving-point impedance realizability ↔ PR function.C → (3): Continued-fraction expansion ↔ Cauer forms.D → (2): Bisection theorem ↔ Bartlett. Verification / Alternative check: Any standard synthesis text (Foster/Cauer/Bartlett) confirms these pairings and the role of PR functions in passive realizations. Why Other Options Are Wrong: Mixing Cauer with bisection or mislabeling PR as a person breaks well-established attributions. Common Pitfalls: Confusing Foster and Cauer canonical forms; forgetting PR conditions (real part ≥ 0 on jω axis). Final Answer: A-1, B-4, C-3, D-2

Question 16

Match communication services to their typical bandwidths: (A) AM broadcast, (B) Telephone (voice channel), (C) Wide-band FM, (D) Television (TV) — with: (1) 10 kHz, (2) 4 kHz, (3) 200 kHz, (4) 7 MHz.

Accepted Answer

Introduction / Context: Each communication service occupies a characteristic bandwidth dictated by modulation method, fidelity requirements, and regulatory standards. Matching these correctly is foundational for spectrum planning and receiver/transmitter design. Given Data / Assumptions: (A) AM broadcast (B) Telephone (POTS) channel (C) Wide-band FM (broadcast FM) (D) TV channel Candidate bandwidths: 10 kHz, 4 kHz, 200 kHz, 7 MHz Concept / Approach: AM broadcast stations transmit audio up to ~5 kHz, leading to ≈10 kHz occupied bandwidth (two sidebands). Voice-grade telephony is limited to ≈300–3400 Hz, i.e., about 4 kHz. Wide-band FM (commercial FM broadcast) allocates roughly 200 kHz channels (allowing for deviation and subcarriers). Analog TV channels historically occupy several MHz; a representative nominal figure here is ≈7 MHz. Step-by-Step Solution: A → (1): AM broadcast ≈ 10 kHz.B → (2): Telephone voice channel ≈ 4 kHz.C → (3): Broadcast FM ≈ 200 kHz spacing/occupancy.D → (4): TV channel on the order of MHz (≈ 7 MHz typical in many standards). Verification / Alternative check: Regulatory tables (e.g., ITU/legacy standards) list these canonical figures; Carson’s rule for FM supports the 200 kHz order for wide-band FM. Why Other Options Are Wrong: Swapping 10 kHz with 4 kHz misstates telephony limits; assigning kHz-scale bandwidth to TV ignores video RF spectrum needs. Common Pitfalls: Confusing narrowband FM (few kHz) with broadcast wide-FM; overlooking guard bands vs occupied bandwidth. Final Answer: A-1, B-2, C-3, D-4

Question 17

In standard TTL logic families, match each parameter to its typical DC level: (A) VOH(min), (B) VIH(min), (C) VOL(max) — choose the correct mapping from the given voltage values.

Accepted Answer

Introduction / Context: Digital logic families (such as classic TTL) specify input and output voltage thresholds to ensure reliable logic-level interpretation. This question asks you to associate three common DC parameters—VOH(min), VIH(min), and VOL(max)—with their typical voltage values in a 5 V TTL system. Understanding these limits helps diagnose interfacing issues and guarantees noise margins when connecting chips from possibly different subfamilies. Given Data / Assumptions: VOH(min): minimum guaranteed HIGH output voltage from a TTL gate. VIH(min): minimum input voltage that a TTL input recognizes as HIGH. VOL(max): maximum guaranteed LOW output voltage from a TTL gate. Typical TTL reference values: 2.4 V (VOH(min)), 2.0 V (VIH(min)), 0.4 V (VOL(max)), and often 0.8 V (VIL(max)) for context. Concept / Approach: The mapping is rooted in standard TTL logic levels. Outputs must drive loads with sufficient headroom above/below the receiving inputs’ thresholds. Therefore, VOH(min) should be higher than VIH(min) to create a positive noise margin; likewise VOL(max) must be lower than VIL(max). Step-by-Step Solution: Match VOH(min) → 2.4 V: This is the minimum a TTL output guarantees in the HIGH state under rated load → A-1.Match VIH(min) → 2.0 V: This is the smallest voltage that a TTL input will reliably treat as HIGH → B-4.Match VOL(max) → 0.4 V: This is the largest voltage a TTL output will reach in the LOW state under load → C-3. Verification / Alternative check: Noise margins (typical): high-side margin = VOH(min) – VIH(min) = 2.4 – 2.0 = 0.4 V; low-side margin = VIL(max) – VOL(max) = 0.8 – 0.4 = 0.4 V. Balanced 0.4 V margins align with canonical TTL datasheets, confirming the mapping. Why Other Options Are Wrong: A-1, B-3, C-4: Assigns VIH(min) = 0.4 V, which is far too low for HIGH recognition in TTL. A-5, B-4, C-3: Maps VOH(min) to 0.8 V, which would collapse the high-level noise margin. A-1, B-5, C-2: Maps VOL(max) to 1.5 V, not acceptable for a LOW level. Common Pitfalls: Confusing input thresholds (VIH/VIL) with output guarantees (VOH/VOL). Assuming CMOS (e.g., rail-to-rail 0–VCC) levels; TTL margins are asymmetric and smaller. Final Answer: A-1, B-4, C-3

Question 18

In C/C++/Java-style boolean expressions, match the following operators to their meanings: (A) &&, (B) ||, (C) = — identify logical AND, logical OR, and assignment.

Accepted Answer

Introduction / Context: Many programming languages use distinct operators for boolean logic and for assignment. Misreading these symbols is a common source of bugs. This matching task reinforces the difference between logical conjunction/disjunction and variable assignment in mainstream C-like languages. Given Data / Assumptions: Operator '&&': used in conditional expressions as logical AND. Operator '||': used as logical OR. Operator '=': used to assign a value to a variable (single equals is not comparison). Short-circuit evaluation semantics typically apply to && and ||. Concept / Approach: Disambiguate symbols by role: logical operators combine boolean results; assignment stores a value. Remember that equality comparison is '==' (not '='), which prevents confusing assignment with testing for equality. Step-by-Step Solution: Map '&&' → Logical AND → A-2.Map '||' → Logical OR → B-3.Map '=' → Assignment operator → C-1. Verification / Alternative check: Consider code: if (x > 0 && y > 0) {...} executes only if both comparisons are true; flag = (x > 0 || y > 0); assigns a boolean result to flag. Using a single '=' inside an if-condition would change a value and is typically flagged by compilers or linters. Why Other Options Are Wrong: A-1, B-2, C-3: Swaps logical AND with assignment and mislabels OR. A-3, B-2, C-1: Interchanges AND/OR semantics. A-1, B-3, C-2: Assigns '=' to logical OR and '||' to assignment—both incorrect. Common Pitfalls: Writing 'if (x = 1)' when you meant 'if (x == 1)', causing unintended assignment. Forgetting short-circuiting: in A && B, B is evaluated only if A is true; in A || B, B is evaluated only if A is false. Final Answer: A-2, B-3, C-1

Question 19

Match control-system controller types to their characteristic operating advantages: (A) Pneumatic controller, (B) Hydraulic controller, (C) Electronic controller — pick the best mapping for explosion-proof operation, high-torque/high-speed actuation…

Accepted Answer

Introduction / Context: Industrial control systems use different controller technologies depending on safety, power, and versatility requirements. Knowing when to apply pneumatic, hydraulic, or electronic controllers is essential for plant design, robotics, and process automation. Given Data / Assumptions: Pneumatic controllers use compressed air—no electrical sparks—making them suitable for hazardous environments. Hydraulic controllers use incompressible fluids and can deliver very high force and rapid response. Electronic controllers (analog/digital) offer programmability, compactness, and easy integration with sensors/PLCs. Concept / Approach: Match each technology to its hallmark advantage: safety in explosive atmospheres (pneumatic), power density and speed (hydraulic), and flexibility/programmability (electronic). Step-by-Step Solution: A (Pneumatic) → intrinsically safe, fire/explosion-proof → 3.B (Hydraulic) → high torque and high speed due to high power density → 2.C (Electronic) → flexible operation, advanced control algorithms, easy tuning → 1. Verification / Alternative check: Standards in process industries (e.g., refineries) commonly mandate pneumatic actuators/controllers in Zone 1/2 hazardous areas, while heavy machinery and robotics often employ hydraulics for force, and general automation uses electronic PID/PLC-based control for adaptability. Why Other Options Are Wrong: A-1, B-3, C-2 or A-1, B-2, C-3: Assigns flexibility to pneumatic or explosion-proof to electronic—both contrary to practice. A-3, B-1, C-2: Claims hydraulics are chiefly flexible while electronics provide high torque—reversed. Common Pitfalls: Assuming electronics are always permissible in explosive atmospheres without proper intrinsically safe barriers. Underestimating maintenance/cleanliness requirements for hydraulic systems. Final Answer: A-3, B-2, C-1

Question 20

Measurement bridges — match each bridge with the primary quantity it measures (or is best suited for).  List I (Bridge) A. Anderson Bridge B. Kelvin Bridge C. Schering Bridge D. Wheatstone Bridge  List II (Primary use) 1. Low resistance measurement …

Accepted Answer

Introduction: This matching problem checks core instrumentation knowledge: which classical AC/DC bridges are best suited to measure inductance, capacitance, and different ranges of resistance. These associations are standard in electrical measurements and metrology. Given Data / Assumptions: A: Anderson Bridge is a derivative of Maxwell bridges focused on inductance measurement. B: Kelvin (Kelvin Double) Bridge eliminates lead/contact errors to measure very low resistances. C: Schering Bridge targets capacitance and dielectric loss (insulation testing). D: Wheatstone Bridge is the general-purpose DC bridge for medium resistances. Concept / Approach: Each bridge exploits balance conditions that isolate the desired unknown. For inductors, bridges compare inductive reactance with known resistive/capacitive elements. For very small resistances, four-terminal (Kelvin) connections bypass lead resistance. For capacitors and dielectrics, Schering uses a lossless standard capacitor and a resistive-capacitive arm to separate capacitance from loss angle. The Wheatstone bridge relies on ratio arms for accurate medium-resistance measurement. Step-by-Step Solution: Map A (Anderson) → inductance → 3.Map B (Kelvin) → low resistance → 1.Map C (Schering) → capacitance/dielectric loss → 4.Map D (Wheatstone) → medium resistance → 2. Verification / Alternative check: Textbook tables of bridges list these canonical uses; laboratory practice confirms that each bridge's topology is optimized for the stated quantity. Why Other Options Are Wrong: Any mapping assigning Kelvin to medium or high resistance ignores its four-terminal low-ohm advantage. Placing Anderson with capacitance or Schering with inductance interchanges distinct AC bridge purposes. Using Wheatstone for very low resistances neglects lead/contact error issues solved by Kelvin. Common Pitfalls: Confusing Maxwell/Anderson variants; remembering that Anderson is specifically tuned for inductance helps. Also, do not assume Wheatstone suits all resistance ranges equally. Final Answer: A-3, B-1, C-4, D-2

Matching Questions Questions