Question 1

C programming — match each bitwise operator symbol in List I with its meaning in List II.  List I (Operator) A. ~ B. & C. | D. ^  List II (Meaning) 1. Bitwise XOR 2. Bitwise AND 3. Bitwise OR 4. One's complement

Accepted Answer

Introduction / Context: Bitwise operators in C manipulate individual bits of integers. They are indispensable in embedded systems, device drivers, networking stacks, and performance-critical code where flags and masks are prevalent. This match-the-following tests recognition of the core operators and their semantics. Given Data / Assumptions: All operators apply to integer operands (signed or unsigned) in C. Evaluation respects C operator precedence and usual integer promotions. We focus on meaning, not precedence or side effects. Concept / Approach: The tilde (~) inverts every bit (one's complement). The ampersand (&) performs bitwise AND, setting a bit only if it is 1 in both operands. The vertical bar (|) performs bitwise OR, setting a bit if it is 1 in either operand. The caret (^) performs bitwise XOR, setting a bit if operands differ at that position. Step-by-Step Solution: Map ~ → one's complement → 4.Map & → bitwise AND → 2.Map | → bitwise OR → 3.Map ^ → bitwise XOR → 1. Verification / Alternative check: Quick test with an 8-bit example: let x = 0b10101010 and y = 0b11001100. Then ~x = 0b01010101, x & y = 0b10001000, x | y = 0b11101110, x ^ y = 0b01100110. These results align with the mapped meanings. Why Other Options Are Wrong: Swapping XOR with OR or AND changes truth conditions and would contradict these bit patterns. Assigning ~ to logical NOT confuses bitwise (~) with logical (!) operators; here we operate on bits, not boolean truth values. Common Pitfalls: Confusing bitwise operators (&, |, ^) with their logical counterparts (&&, ||). Also, forgetting that ~ on signed integers is defined via two's complement representation and can produce negative values. Final Answer: A-4, B-2, C-3, D-1

Question 2

Magnetic materials — match each class in List I with the correct microscopic ordering description in List II.  List I (Class) A. Paramagnetic B. Ferromagnetic C. Antiferromagnetic D. Ferrimagnetic  List II (Microscopic description) 1. All dipoles al…

Accepted Answer

Introduction / Context: Magnetic ordering arises from atomic dipole interactions and crystal structure. Recognizing paramagnetic, ferromagnetic, antiferromagnetic, and ferrimagnetic arrangements helps in materials selection for transformers, recording heads, permanent magnets, and microwave ferrites. Given Data / Assumptions: Room-temperature qualitative descriptions are used. “Dipoles” refer to atomic or ionic magnetic moments on crystallographic sublattices. We ignore thermal transitions (Curie/Neél temperatures) in this classification task. Concept / Approach: Paramagnetism features randomly oriented moments that weakly align with external fields (no long-range order). Ferromagnetism shows parallel alignment of neighboring moments, giving strong net magnetization. Antiferromagnetism has equal and opposite sublattices, cancelling net magnetization. Ferrimagnetism also has opposing sublattices, but unequal magnitudes yield a nonzero net moment (e.g., magnetite Fe3O4). Step-by-Step Solution: A (Paramagnetic) → random orientation → 4.B (Ferromagnetic) → parallel alignment → 1.C (Antiferromagnetic) → equal and opposite → 2.D (Ferrimagnetic) → opposite, unequal magnitudes → 3. Verification / Alternative check: Hysteresis loops: paramagnets show no loop; ferromagnets show large remanence and coercivity; antiferromagnets have near-zero net M; ferrimagnets behave like ferromagnets but with lower saturation due to partial cancellation. Why Other Options Are Wrong: Swapping 2 and 3 confuses antiferromagnetic (equal magnitudes) with ferrimagnetic (unequal magnitudes). Assigning order to paramagnets contradicts their random thermal orientation without applied field. Common Pitfalls: Thinking ferrimagnetism is just “weak ferromagnetism.” It is distinct: two sublattices oppose with different magnitudes, yielding a net moment and often high Curie temperatures. Final Answer: A-4, B-1, C-2, D-3

Question 3

Measuring instruments — match each instrument in List I with its correct classification/use in List II.  List I (Instrument) A. Tangent galvanometer B. Moving-coil instrument (PMMC) C. Household energy meter D. Electrostatic instrument  List II (Cla…

Accepted Answer

Introduction / Context: Instrument classification clarifies what quantity an instrument measures and whether it serves as a primary standard or a secondary indicating device. Correct mapping is vital for calibration labs, power metering, and electrical measurements courses. Given Data / Assumptions: Tangent galvanometer uses the tangent law to relate current to deflection in Earth’s magnetic field. PMMC (permanent-magnet moving-coil) instruments are inherently DC devices unless rectified for AC. An energy meter integrates power over time to register watt-hours or kilowatt-hours. Electrostatic instruments respond to electric field energy and are suited to voltage measurement, even at high voltage. Concept / Approach: Identify whether each instrument is absolute (primary standard), DC-only, integrating, or voltage-only. The tangent galvanometer is an absolute instrument because current can be determined from geometry and field constants. PMMC is accurate for DC. Energy meters are integrating instruments by design. Electrostatic instruments measure force proportional to V^2, ideal for high-voltage measurement and essentially limited to voltage. Step-by-Step Solution: A (Tangent galvanometer) → absolute instrument → 4.B (Moving-coil/PMMC) → DC only → 1.C (Household energy meter) → integrating instrument → 2.D (Electrostatic instrument) → for voltage only → 3. Verification / Alternative check: Textbook classifications: PMMC needs rectifiers for AC; induction-type meters integrate power over time; electrostatic voltmeters measure potential difference with negligible current draw; tangent galvanometer can be used to derive absolute current based on known Earth's field and coil geometry. Why Other Options Are Wrong: Assigning PMMC to AC would ignore its magnetic flux dependency and rectification need. Labeling the energy meter otherwise than integrating contradicts its function. Electrostatic instruments are not general-purpose ammeters or power meters. Common Pitfalls: Confusing “absolute” with “precision.” Absolute refers to principle of operation not requiring prior calibration against another meter (within limits), unlike many secondary instruments. Final Answer: A-4, B-1, C-2, D-3

Question 4

Transducers and measurement principles — match each device in List I with the corresponding operation mapping in List II.  List I (Transducer) A. Bourdon tube B. Hot-wire anemometer C. Hydrometer D. Pitot tube  List II (Operation) 1. Fluid flow/velo…

Accepted Answer

Introduction / Context: Many sensors convert a physical quantity into a more convenient intermediate signal such as displacement, resistance, or pressure. Recognizing these mappings helps in selecting appropriate transducers for flow, density, pressure, and velocity measurements in instrumentation and process control. Given Data / Assumptions: Bourdon tube is a mechanical pressure sensor producing tip displacement. Hot-wire anemometer uses convective cooling of a heated wire to infer flow velocity from resistance changes. Hydrometer indicates specific gravity by floating height (displacement principle). Pitot tube converts dynamic pressure from velocity into measurable pressure difference. Concept / Approach: Map each device to its primary transduction: pressure → displacement (Bourdon), velocity/flow → resistance change (hot-wire), specific gravity → displacement (hydrometer buoyancy), and velocity → pressure (Pitot dynamic pressure to a manometer or transducer). Step-by-Step Solution: A (Bourdon tube) → pressure to displacement → 3.B (Hot-wire anemometer) → flow velocity affects wire cooling → resistance change → 1.C (Hydrometer) → specific gravity sets float level (displacement) → 4.D (Pitot tube) → velocity head to pressure (stagnation) → 2. Verification / Alternative check: For the Pitot tube, Bernoulli's relation gives velocity from measured differential pressure; for the hot-wire, King's law relates heat loss to velocity, which in turn changes resistance; for the Bourdon tube, elastic deformation converts pressure to tip displacement proportional to applied pressure; a hydrometer follows Archimedes’ principle. Why Other Options Are Wrong: Swapping the hot-wire and pitot mappings confuses thermal and pressure-based flow measurement principles. Assigning Bourdon to electrical resistance ignores its mechanical nature. Mapping hydrometer to pressure or resistance disregards buoyancy-based operation. Common Pitfalls: Assuming all flow meters are pressure-based; thermal anemometry is distinct. Also, mis-spelling “Bourdon” (not “Bourden”) is common in exams. Final Answer: A-3, B-1, C-4, D-2

Question 5

Match the parts of an analog moving-coil (PMMC) instrument to their functions. List I (Part) List II (Function) A. Former 1. Produces deflecting torque (in the magnetic field) B. Coil 2. Provides the base on which the coil is wound C. Core 3. Makes …

Accepted Answer

Introduction / Context: PMMC (Permanent-Magnet Moving-Coil) instruments convert electrical quantities into mechanical deflection. Knowing what each mechanical part does is essential for understanding accuracy, damping, and scale linearity in measuring instruments used in electrical engineering labs. Given Data / Assumptions: A PMMC meter has a light rectangular coil, a non-magnetic former, soft-iron core pieces that shape the field, and spiral hairsprings. The permanent magnet establishes the working magnetic field; interactions produce torque. We match four labeled parts to their correct roles. Concept / Approach: Deflecting torque is produced when a current-carrying coil sits in a magnetic field. A former is the mechanical support for the coil winding. Soft-iron pole pieces/core make the field radial so that the torque remains proportional to current for a linear scale. Spiral springs provide restoring (controlling) torque and also carry current to the moving coil. Step-by-Step Solution: Identify the former as the base for the coil ⇒ A-2.Recognize the coil as the source of electromagnetic deflection ⇒ B-1.Assign the core/pole pieces to shaping a radial field ⇒ C-3.Attribute the spring to providing controlling torque ⇒ D-4. Verification / Alternative check: Linear scale behavior in PMMC instruments arises when the field is radial (core's function) and torque is proportional to coil current. The spring's opposing torque yields an equilibrium angle proportional to current, confirming the mapping. Why Other Options Are Wrong: Pairing the former with deflecting torque confuses mechanical support with electromechanical action. Assigning the spring to produce deflection ignores its restoring role. Swapping core and spring roles contradicts meter construction theory. Common Pitfalls: Mixing up 'former' and 'core': the former holds the coil; the core shapes the field. Also forgetting that springs both control torque and provide electrical connections. Final Answer: A-2, B-1, C-3, D-4

Question 6

Match common biomedical instruments to what they primarily measure or help diagnose. List I (Instrument) List II (Use) A. Electro-encephalograph 1. Diagnostic tool for heart ailments B. Electro-cardiograph 2. Diagnostic tool for brain ailments C. Sp…

Accepted Answer

Introduction / Context: Biomedical instruments are foundational to clinical diagnostics. Correctly associating devices with their clinical roles is important for students in biomedical, electronics, and instrumentation engineering. Given Data / Assumptions: Electro-encephalograph (EEG) measures brain electrical activity. Electro-cardiograph (ECG) records heart electrical activity. Sphygmomanometer measures arterial blood pressure. Stethoscope is an acoustic tool to auscultate heart and lung sounds. Concept / Approach: Match each instrument to its principal clinical function: EEG→brain, ECG→heart, sphygmomanometer→BP, stethoscope→listening to beats/sounds. This is a direct knowledge recall with no calculations. Step-by-Step Solution: EEG is used for brain diagnostics such as epilepsy ⇒ A-2.ECG evaluates cardiac rhythm and conduction ⇒ B-1.Sphygmomanometer measures systolic/diastolic BP ⇒ C-3.Stethoscope is used to hear heart sounds and pulse ⇒ D-4. Verification / Alternative check: Hospital workflows: neurologists rely on EEG; cardiologists on ECG; nurses use sphygmomanometers for vitals; stethoscopes are ubiquitous for auscultation. These confirm the mapping. Why Other Options Are Wrong: Swapping EEG with ECG misassigns organ systems. Attributing BP measurement to a stethoscope confuses accessory use (Korotkoff sounds) with the measuring device. Common Pitfalls: Confusing the role of the stethoscope during manual BP measurement: it detects sounds, but pressure is measured by the cuff/gauge (sphygmomanometer). Final Answer: A-2, B-1, C-3, D-4

Question 7

Match basic computing/data terms to their definitions. List I (Term) List II (Definition) A. Interface 1. A measure of the rate of data transmission B. A bit 2. A binary digit (0 or 1) C. Baud speed 3. The common boundary between subsystems or devic…

Accepted Answer

Introduction / Context: Core vocabulary in computing and communications often appears in exams. Understanding what an interface is, what a bit represents, and what baud (symbol rate) measures helps avoid conceptual errors when reading specifications. Given Data / Assumptions: Interface refers broadly to boundaries across which systems interact (hardware or software). Bit is the atomic unit of digital information: 0 or 1. Baud is symbols per second, a rate measure for signaling. Concept / Approach: We match each List I term to the best List II definition: interface→boundary, bit→binary digit, baud speed→rate of data transmission (symbol rate). Although baud and bits per second can differ with multilevel coding, baud remains a measure of signaling events per second. Step-by-Step Solution: Interface is the common boundary ⇒ A-3.A bit is a binary digit ⇒ B-2.Baud speed measures signaling rate ⇒ C-1. Verification / Alternative check: Serial links list 9600 baud, 115200 baud, etc. Documentation distinguishes bps (bits per second) from baud when modulation encodes multiple bits per symbol, reinforcing that baud is a rate measure. Why Other Options Are Wrong: Calling a bit “a rate” confuses quantity of information with transmission speed. Defining an interface as a number is incorrect; it is a boundary/contract between subsystems. Common Pitfalls: Assuming baud equals bits per second in all cases; equality holds only for binary signaling with one bit per symbol. Final Answer: A-3, B-2, C-1

Question 8

Microwave/waveguide fundamentals: match each statement to its correct concept. List I (Statement) List II (Concept) A. Ratio of maximum stored energy to energy lost per cycle 1. Propagation constant (β = ω / v_p) B. TEM mode in a lossless medium 2. …

Accepted Answer

Introduction / Context: This item links core microwave concepts: quality factor, propagation constant, cutoff, and waveguide modes. These fundamentals are repeatedly used in cavity design, transmission-line analysis, and mode identification. Given Data / Assumptions: Lossless media are assumed unless stated otherwise. Propagation along z uses phase velocity v_p and angular frequency ω. Hollow circular waveguides support TE/TM modes; TEM does not propagate in single-conductor waveguides. Concept / Approach: Quality factor Q is defined as stored energy / energy lost per radian or per cycle (proportional definition used in exams). For TEM lines (e.g., coax), cutoff frequency is zero. The spatial phase constant β equals ω / v_p. Discussions about the lowest cutoff mode belong to specific waveguide geometries such as circular guides (TE11 is lowest). Step-by-Step Solution: A: “Ratio of stored to lost energy per cycle” ⇒ Q ⇒ A-3.B: TEM in a lossless medium has f_c = 0 ⇒ B-2.C: ω / v_p defines the phase constant β ⇒ C-1.D: “Lowest cutoff mode” is a property we discuss for circular waveguides (TE11) ⇒ D-4. Verification / Alternative check: Standard formulas: β = ω / v_p; for TEM on ideal lines, β = ω√(L′C′) and no cutoff. For cavities/waveguides, Q = 2π * (energy stored / energy lost per cycle), consistent with statement A. Why Other Options Are Wrong: Swapping Q with β confuses energy storage with phase progression. Assigning “cutoff zero” to non-TEM modes is incorrect for hollow waveguides. Common Pitfalls: Believing TEM can exist in a single-conductor hollow guide; TEM requires two conductors or a return path. Final Answer: A-3, B-2, C-1, D-4

Question 9

Match communication systems/receivers to their characteristic techniques. List I List II A. Costas receiver 1. Vestigial sideband (VSB) B. Stereo multiplexing (radio) 2. Demodulating DSB-SC (coherent) C. TV broadcasting 3. FM radio broadcasting (mul…

Accepted Answer

Introduction / Context: Different communication services use different modulation/detection methods. Matching them quickly is a staple of communications examinations and interviews. Given Data / Assumptions: Costas loop is a coherent detector for DSB-SC or suppressed-carrier systems. FM stereo broadcasting uses multiplexing (L+R, L−R with a pilot). Analog TV broadcasting traditionally used AM-VSB for the video channel. Concept / Approach: Map each system to the defining modulation/detection method: Costas→DSB-SC demodulation, stereo multiplex→FM radio system, TV broadcast→VSB to reduce bandwidth while maintaining low-frequency fidelity. Step-by-Step Solution: Recognize the Costas receiver as a PLL-based coherent detector for suppressed carriers ⇒ A-2.Recall FM stereo uses a 19 kHz pilot and 38 kHz subcarrier for L−R ⇒ B-3.Recall broadcast TV used VSB AM for video to conserve spectrum ⇒ C-1. Verification / Alternative check: Block diagrams in standard texts show Costas loops recovering carrier phase; FM stereo multiplex standards (e.g., 75 kHz deviation, pilot) validate B; NTSC/PAL video spectrum masks show VSB, confirming C. Why Other Options Are Wrong: Assigning VSB to FM stereo is incorrect; FM multiplex does not use vestigial sidebands. Claiming Costas is for VSB confuses coherent DSB-SC detection with amplitude filtering techniques. Common Pitfalls: Mixing up Costas with a simple envelope detector; the latter requires an unsuppressed carrier and is not suitable for DSB-SC. Final Answer: A-2, B-3, C-1

Question 10

8085 instruction effects on flags: match each instruction to the correct flag behavior. List I (Instruction) List II (Flag behaviour) A. ORI 1. CY reset B. DAA 2. CY reset and AC reset C. PCHL (copy HL→PC) 3. S, Z, AC, P, CY flags affected 4. S, Z, …

Accepted Answer

Introduction / Context: On the 8085 microprocessor, arithmetic/logic instructions set or reset condition flags. Correctly recalling which flags change for ORI, DAA, and PCHL avoids subtle debugging errors and is frequently tested. Given Data / Assumptions: ORI performs a bitwise OR with immediate data. DAA adjusts the accumulator after BCD addition, affecting multiple flags. PCHL loads the program counter from HL and is a logical jump (no arithmetic). Concept / Approach: For ORI/XRI/ANI, 8085 specifies CY and AC are reset to 0; S, Z, and P are set per result (affected). DAA can alter S, Z, AC, P, and CY depending on the adjust; thus many flags are affected. PCHL is a register-to-PC transfer and does not modify flags. Step-by-Step Solution: ORI: emphasize the distinctive rule CY=0 and AC=0 (and result flags adjust). In the given list, the closest explicit mapping is “CY reset and AC reset” ⇒ A-2.DAA: affects S, Z, AC, P, CY ⇒ B-3.PCHL: a control transfer with no arithmetic/logic ⇒ flags unchanged ⇒ C-5. Verification / Alternative check: 8085 datasheets list flag effects: ORI clears CY and AC; DAA may set/reset CY/AC and updates S, Z, P; PCHL does not affect flags. These corroborate the chosen mapping. Why Other Options Are Wrong: Mapping PCHL to any flag changes contradicts documentation. Assigning only “S, Z, P modified” to ORI omits the guaranteed clearing of CY and AC emphasized by 8085 rules. Common Pitfalls: Confusing ORI with ADD/ADI (which may set carry), and assuming DAA only affects AC without considering a possible carry out after adjustment. Final Answer: A-2, B-3, C-5

Question 11

Match functional blocks in a classical servo control system to representative hardware. List I (Functional component) List II (Device example) A. Error detector 1. Three-phase fractional-horsepower induction motor (FHP IM) B. Servo motor 2. Synchro …

Accepted Answer

Introduction / Context: Classical servo systems comprise an error detector, a power amplifier, a servo motor, and a feedback element. Recognizing typical hardware that implements each block is crucial in control systems and mechatronics. Given Data / Assumptions: Error detector compares reference and feedback signals. Servo motor converts the amplified control signal into mechanical motion. Amplifier raises signal power to drive the motor. Feedback element measures speed or position to close the loop. Concept / Approach: Synchros (transmitter and control transformer) form a classic error detector by producing a voltage proportional to angular difference. An armature-controlled FHP DC motor is a canonical servo motor due to easy speed control. Amplidynes (rotating amplifiers) historically served as powerful control amplifiers. A tacho generator delivers a voltage proportional to speed for feedback. Step-by-Step Solution: Error detector → synchro pair ⇒ A-2.Servo motor → armature-controlled DC motor ⇒ B-4.Amplifier → amplidyne ⇒ C-5.Feedback element → tacho generator ⇒ D-3. Verification / Alternative check: Control textbooks show synchro error detectors in position-control servos; DC servomotors are used for precise control; amplidynes provided high power gain before solid-state drives; tachogenerators remain common for speed feedback. Why Other Options Are Wrong: Mapping the amplifier to an induction motor misunderstands block roles. Using a three-phase induction motor as the standard servo motor complicates control; DC servomotors are the classical choice for fine control. Common Pitfalls: Confusing sensors (tacho) with error detectors (synchros); the former measures speed directly, while the latter measures difference between commanded and actual positions. Final Answer: A-2, B-4, C-5, D-3

Question 12

Control engineering – Match control action to a typical real-world application List I (Control action) A. On–off control B. Proportional control C. Cascade control (nested loops) D. Digital (discrete-step) control  List II (Application)  Steam kettl…

Accepted Answer

Introduction / Context: This matching problem connects four classic control strategies with representative applications. Recognizing the “signature” use cases of on–off, proportional, cascade, and digital control helps you pick the right controller architecture in practical systems ranging from household appliances to industrial servos. Given Data / Assumptions: A: On–off control is a two-state (bang–bang) action with hysteresis. B: Proportional (P) control output is proportional to error. C: Cascade control means an outer loop drives a setpoint for an inner loop. D: Digital (discrete-step) control here implies selectable discrete settings (not continuous). Applications listed: domestic refrigerator, elevator, robot servo, and multi-setting kettle. Concept / Approach: Map each control strategy to the most characteristic application: On–off control is ubiquitous in thermostatic systems (refrigerators). Proportional control is a basic building block in motion control, such as elevators. Cascade control is widely used in multi-loop precision systems like robots (inner velocity/current loop, outer position loop). Digital step control suits devices offering discrete power levels like a multi-setting kettle. Step-by-Step Solution: A (On–off) → 4 (Domestic refrigerator thermostat).B (Proportional) → 2 (Elevator speed/position P-based regulation).C (Cascade) → 3 (Robot positioning with inner/outer loops).D (Digital) → 1 (Steam kettle with discrete power settings). Verification / Alternative check: Compare with standard control texts: thermostats are canonical on–off; elevators commonly use proportional (often augmented to PID); robotics frequently employs cascaded loops; household devices with “level 1–5” power are discrete/digital in nature. Why Other Options Are Wrong: Pairing on–off with elevators or robots ignores the need for smooth motion; assigning cascade to kettles provides no benefit; mapping proportional to refrigerators would cause excessive cycling without hysteresis. Common Pitfalls: Confusing “digital control” (discrete-time algorithms) with “digital steps.” Here, “digital” clearly refers to discrete selectable power levels. Also, cascade implies a nested inner/outer loop, not just two separate controllers. Final Answer: A-4, B-2, C-3, D-1.

Question 13

Dimensional analysis – Match circuit quantities to their dimensional formulas List I (Quantity) A. Resistance B. Inductance C. Capacitance  List II (Dimensions in M–L–T–I form)  M^-1 L^-2 T^4 I^2  M L^2 T^-2 I^-2  M L^2 T^-3 I^2 ← (note: commonly wr…

Accepted Answer

Introduction / Context: Engineering quantities can be expressed via base dimensions Mass (M), Length (L), Time (T), and Current (I). Remembering these helps verify formulas and catch unit mistakes in circuit analysis and electromagnetics. Given Data / Assumptions: Ohm (resistance) = Volt/Ampere. Henry (inductance) = Volt·second/Ampere. Farad (capacitance) = Coulomb/Volt. Standard base: V = M L^2 T^-3 I^-1, A = I, Q = I·T. Concept / Approach: Compute dimensional forms from definitions: R = V/A, L = (V·s)/A, C = Q/V. Substitute base dimensions and simplify exponents carefully, paying attention to powers of I (current) because sign errors there are common in printed tables. Step-by-Step Solution: Resistance R: V/A → (M L^2 T^-3 I^-1) / I = M L^2 T^-3 I^-2 → matches item 3 (noting the common convention I^-2).Inductance L: (V·s)/A → (M L^2 T^-3 I^-1 · T) / I = M L^2 T^-2 I^-2 → matches item 2.Capacitance C: Q/V → (I·T) / (M L^2 T^-3 I^-1) = I^2 T^4 / (M L^2) = M^-1 L^-2 T^4 I^2 → matches item 1. Verification / Alternative check: Cross-check with any EM/circuits handbook: R → M L^2 T^-3 I^-2, L → M L^2 T^-2 I^-2, C → M^-1 L^-2 T^4 I^2. Minor typographic variances sometimes flip the sign on I; the physical relation clarifies the correct exponents. Why Other Options Are Wrong: Options that swap R with C or L contradict the base-unit derivations above; particularly, resistance cannot have the same T power as inductance. Common Pitfalls: Forgetting that V scales as M L^2 T^-3 I^-1; mishandling current powers when dividing by A (I), which should decrease the exponent by one. Final Answer: A-3, B-2, C-1.

Question 14

Opto-electronic devices – Match each device to its defining behavior List I (Device) A. Laser B. Solar cell C. Photodiode D. LED  List II (Behavior)  Emits monochromatic light of low intensity  Consumes electrical power due to incident light (revers…

Accepted Answer

Introduction / Context: Opto-electronic components are categorized by whether they generate light, detect light, or convert light directly into electrical power. Matching these devices with their hallmark behaviors is essential for selecting parts in communication links, sensing, and illumination. Given Data / Assumptions: Laser produces coherent, narrow-spectrum (monochromatic) light with high intensity. Solar cell operates in photovoltaic mode, delivering power to a load from incident light. Photodiode, when reverse-biased, acts as a light detector drawing current (consuming electrical power) proportional to illumination. LED emits light of relatively low intensity and broader spectrum compared to lasers. Concept / Approach: Identify each device’s “signature” role: high-intensity monochromatic emission → laser; power generation → solar cell; photo-detection with bias power → photodiode; low-intensity emission → LED. While photodiodes can also operate in photovoltaic mode, the most common detection mode in receivers is reverse-biased (photoconductive), matching the statement given. Step-by-Step Solution: A (Laser) → 4 (high-intensity monochromatic emission).B (Solar cell) → 3 (delivers power to a load).C (Photodiode) → 2 (reverse-biased detector consuming electrical power while converting light to current).D (LED) → 1 (low-intensity, quasi-monochromatic light emission). Verification / Alternative check: Check typical link budgets: lasers drive fiber optics; LEDs for indicators/illumination; photodiodes in reverse-bias mode for receivers; solar cells power calculators/satellites from light alone. Why Other Options Are Wrong: Mapping “power delivery” to LED or photodiode conflicts with their detector/emitter roles. Assigning “high intensity” to LED ignores the coherent power density of lasers. Common Pitfalls: Confusing photodiode photovoltaic vs. photoconductive modes; equating laser and LED because both emit light—only lasers are coherent and typically far higher intensity. Final Answer: A-4, B-3, C-2, D-1.

Question 15

Device characteristics – Match characteristic to the appropriate device List I (Characteristic) A. Voltage-controlled device B. Current-controlled device C. Conductivity modulation device D. Negative-conductance device  List II (Device)  BJT  UJT  F…

Accepted Answer

Introduction / Context: Different semiconductor devices are categorized by how their control input affects conduction and by special effects like negative conductance or conductivity modulation. Matching these attributes helps in quickly identifying suitable parts for amplification, switching, oscillation, or triggering. Given Data / Assumptions: FETs are voltage-controlled (gate modulates channel with negligible input current). BJTs are current-controlled (collector current depends on base current). UJT exhibits conductivity modulation in its emitter-triggered behavior and negative-resistance region often used for relaxation oscillators. IMPATT diodes are classic negative-conductance microwave diodes due to impact ionization and transit-time effects. Concept / Approach: Assign each characteristic to the best-known exemplar: voltage control → FET; current control → BJT; conductivity modulation → UJT (emitter injection alters channel conductivity); negative conductance → IMPATT (microwave oscillators/amplifiers in the negative-resistance region). Step-by-Step Solution: A (Voltage-controlled) → 3 (FET).B (Current-controlled) → 1 (BJT).C (Conductivity modulation) → 2 (UJT).D (Negative conductance) → 4 (IMPATT diode). Verification / Alternative check: Datasheets and textbooks consistently describe FET gate control as voltage-driven, BJTs as current-driven, UJTs as conductivity-modulated triggers, and IMPATTs as negative-resistance microwave devices. Why Other Options Are Wrong: Swapping BJT and FET reverses fundamental control laws; attributing negative conductance to BJT or UJT confuses low-frequency negative resistance with the high-frequency negative conductance of IMPATT. Common Pitfalls: Assuming every device with a negative-resistance region is a “negative-conductance” microwave device; conflating MOSFET gate leakage with current control. Final Answer: A-3, B-1, C-2, D-4.

Question 16

Classical frequency-domain methods – Match contributor to the associated plot/technique List I (Contributor) A. Bode B. Evans C. Nyquist  List II (Technique)  Asymptotic magnitude/phase plots (Bode plots)  Polar plots based on encirclement criterion…

Accepted Answer

Introduction / Context: Bode plots, root locus, and Nyquist plots are cornerstone tools in classical control design. Each technique is associated with a specific historical contributor and serves a distinct purpose in assessing stability and shaping dynamics in the frequency domain. Given Data / Assumptions: Bode: log-magnitude and phase plots vs. frequency with asymptotic approximations. Evans: root-locus method tracing closed-loop pole movement as gain varies. Nyquist: polar plot of open-loop response to apply the Nyquist stability criterion. Concept / Approach: Match name to technique: Bode ↔ asymptotic frequency plots; Evans ↔ root locus (geometry of closed-loop poles); Nyquist ↔ polar encirclement of the critical point in the complex plane to infer closed-loop stability. Step-by-Step Solution: A (Bode) → 1 (Asymptotic magnitude/phase plots).B (Evans) → 3 (Root-locus technique).C (Nyquist) → 2 (Polar plots/Nyquist criterion). Verification / Alternative check: Any introductory control textbook or standards like ISO/IEEE tutorials confirm these canonical associations. Why Other Options Are Wrong: Pairing Bode with polar plots or Evans with Bode plots mixes distinct methodologies with different graphical constructions and interpretations. Common Pitfalls: Confusing Nyquist polar plots with Nichols charts; mistaking asymptotic Bode lines for exact frequency response (they are approximations refined near corner frequencies). Final Answer: A-1, B-3, C-2.

Question 17

Control Systems: Match Concepts to Their Descriptions  List I A. Very low response at very high frequencies B. Over shoot C. Synchro-control transformer output  List II  Low-pass system  Velocity damping  Natural frequency  Phase-sensitive modulatio…

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Introduction / Context: This matching problem revisits three common control-engineering ideas: the frequency response shape of a low-pass system, the meaning of overshoot in transient response, and the characteristic output of a synchro-control transformer. Knowing these associations strengthens intuition for both frequency-domain and time-domain behavior, as well as electromechanical sensor interfaces. Given Data / Assumptions: A: Very low response at very high frequencies. B: Overshoot in a step response. C: Synchro-control transformer output signal nature. List II contains: Low-pass system, Velocity damping, Natural frequency, Phase-sensitive modulation, Damping ratio. Concept / Approach: A low-pass system attenuates high-frequency content; therefore its gain is small (very low response) at very high frequencies. Step-response overshoot depends primarily on the damping ratio (zeta) of the dominant second-order dynamics. A synchro-control transformer is inherently phase sensitive; its output depends on the phase (angle) between rotor and stator fields and resembles phase-sensitive modulation of an error angle. Step-by-Step Solution: A → The hallmark of a low-pass system is high gain at low frequency and strongly reduced gain at high frequency ⇒ 1.B → Overshoot increases as damping ratio decreases (for a fixed natural frequency). Thus, overshoot is governed by the damping ratio ⇒ 5.C → A synchro-control transformer's secondary voltage is proportional to sin of the error angle and its polarity depends on relative phase, making the detection phase-sensitive ⇒ 4. Verification / Alternative check: Second-order step-response formulas show peak overshoot M_p = exp(−πζ / sqrt(1 − ζ^2)), directly linking overshoot to damping ratio. Synchro/control-transformer schematics and small-angle approximations (V_out ≈ K * θ_error) confirm phase-sensitive behavior. Bode plots of low-pass filters demonstrate large attenuation as frequency increases. Why Other Options Are Wrong: Velocity damping (2) is a particular damping implementation, not the general parameter determining overshoot. Natural frequency (3) sets oscillation speed, but overshoot magnitude hinges mainly on damping ratio. Other pairings misrepresent the fundamental definitions. Common Pitfalls: Confusing the cause (damping ratio) with the mechanism (velocity feedback) for overshoot; also, mistaking a band-pass/notch behavior for low-pass when describing high-frequency attenuation. Final Answer: A-1, B-5, C-4

Question 18

Planar Transmission Media: Match Each Line Type to Its Name  List I (Structures) A. Slotline B. Coplanar line C. Microstrip  List II (Labels)  Slot line  Coplanar line  Microstrip

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Introduction / Context: Modern RF and microwave printed-circuit technologies commonly use microstrip, coplanar, and slotline structures. Distinguishing these by geometry is essential for correct design of filters, couplers, transitions, and antenna feeds on planar substrates. Given Data / Assumptions: Microstrip: signal trace on one side of a dielectric with a continuous ground plane on the opposite side. Coplanar line (often CPW with ground): center conductor flanked by ground planes on the same side of the dielectric, with or without a backside ground. Slotline: narrow slot etched in an otherwise continuous ground plane; fields concentrate across the slot. Concept / Approach: Match each canonical geometry to its standard name. The distinctions hinge on where the conductors and ground planes are located and where the dominant fields are confined. Step-by-Step Solution: A (Slotline) → a slot cut in the ground plane supporting odd-mode fields across the slot ⇒ 1.B (Coplanar line) → conductors and grounds on the same surface; characteristic gaps define impedance ⇒ 2.C (Microstrip) → top trace over a solid back ground plane ⇒ 3. Verification / Alternative check: Field simulations and textbook cross-sections show microstrip's primarily quasi-TEM mode with fields largely between top trace and bottom ground; CPW fields split across coplanar gaps; slotline confines fields in the slot itself. Why Other Options Are Wrong: Swapping names confuses grounding topology and field distributions, leading to wrong impedance and radiation expectations. Common Pitfalls: Assuming coplanar lines always require no backside ground; in practice, CPW with ground often includes a backside ground tied by vias for shielding. Final Answer: A-1, B-2, C-3

Question 19

Classical Network Synthesis Forms: Match Realization Form to Its Ladder/Branch Description  List I (Form) A. Cauer I B. Cauer II C. Foster I D. Foster II  List II (Network Description)  L in series arm and C in shunt arm of a ladder  C in series arm…

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Introduction / Context: For positive-real driving-point functions of passive LC networks, Foster and Cauer forms offer canonical realizations. Recognizing which description corresponds to each form helps when translating a target impedance or admittance into a practical ladder or branch network. Given Data / Assumptions: Lossless synthesis context (L and C elements only). Driving-point realizations (one-port networks). Descriptions emphasize whether elements appear in series/shunt ladder arms, or as sums of resonant branches. Concept / Approach: Cauer forms arise from continued-fraction expansions, producing ladders that begin with series L (Cauer I) or series C (Cauer II). Foster forms arise from partial-fraction expansions: Foster I yields a series chain of parallel LC branches; Foster II yields a parallel network of series LC branches. Step-by-Step Solution: A (Cauer I) → ladder starts with series L, then shunt C ⇒ 1.B (Cauer II) → ladder starts with series C, then shunt L ⇒ 2.C (Foster I) → series of parallel L||C resonators ⇒ 3.D (Foster II) → parallel of series L–C resonators ⇒ 4. Verification / Alternative check: Expanding an impedance via partial fractions produces summands resembling resonant terms realizable as either parallel or series LC branches, directly mapping to Foster I/II. Continued fractions cascade series/shunt elements, matching Cauer ladders. Why Other Options Are Wrong: Swapping Foster I and II reverses series/parallel roles; swapping Cauer I and II reverses which element appears in the series arm first. Common Pitfalls: Confusing impedance versus admittance realizations; one must stay consistent with the form derived from the chosen expansion. Final Answer: A-1, B-2, C-3, D-4

Question 20

Binary Coding Practice: Match Decimal Values to Their 8-bit Binary Equivalents  List I (Decimal) A. 45 B. 90 C. 180 D. 210  List II (8-bit Binary)  10110100  11010010  01011010  00101101  10101000

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Introduction / Context: Digital systems frequently require quick translation between decimal and binary. This problem reinforces binary conversion for common values, ensuring confidence when reading registers, bitmaps, or instruction encodings. Given Data / Assumptions: 8-bit unsigned representation (leading zeros permitted). Decimal values: 45, 90, 180, 210. Binary candidates supplied as 8-bit strings. Concept / Approach: Convert each decimal number to binary using successive division by 2 or by decomposing into powers of 2. Then match to the list of 8-bit patterns. Step-by-Step Solution: A: 45 = 32 + 8 + 4 + 1 = 0010 1101 → 00101101 ⇒ item 4.B: 90 = 64 + 16 + 8 + 2 = 0101 1010 → 01011010 ⇒ item 3.C: 180 = 128 + 32 + 16 + 4 = 1011 0100 → 10110100 ⇒ item 1.D: 210 = 128 + 64 + 16 + 2 = 1101 0010 → 11010010 ⇒ item 2. Verification / Alternative check: Hex cross-check: 45 = 0x2D = 0010 1101; 90 = 0x5A = 0101 1010; 180 = 0xB4 = 1011 0100; 210 = 0xD2 = 1101 0010. Hex-to-binary mapping confirms the 8-bit strings. Why Other Options Are Wrong: Each incorrect option mis-assigns at least one decimal-to-binary mapping, which will break in arithmetic or bit-test verification. Common Pitfalls: Dropping leading zeros (acceptable visually but confusing in fixed-width contexts) or mixing nibble order when transcribing hex to binary. Final Answer: A-4, B-3, C-1, D-2

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