(SEM IV) THEORY EXAMINATION 2024-25 ELECTRONICS ENGINEERING

The uploaded document is the B.Tech Semester IV Theory Examination Paper (2024–25) for the subject BOE409 – Electronics Engineering. This official university exam paper is designed to comprehensively assess a student’s understanding of fundamental electronic components, semiconductor behavior, device characteristics, rectifier operations, field-effect transistor concepts, operational amplifier applications, and electronic measurement instruments. The exam carries a total of 70 marks and must be completed within 3 hours. The paper is presented in a bilingual format — English and Hindi — ensuring clarity and accessibility for students irrespective of their language preference.
 

The first part of the paper, Section A, contains seven short-answer questions, each worth 2 marks, and all are compulsory. These questions focus on basic conceptual understanding. Students are asked to list the properties of semiconductor materials, explain static and dynamic resistance in a PN-junction diode, and describe the operating principle of an LED. Additional questions include drawing and explaining the voltage doubler circuit, describing key parameters of a JFET, explaining the characteristics of an ideal operational amplifier, and explaining how continuity is checked using a digital multimeter. Although brief, this section ensures that students have a strong foundation in the core concepts of electronics before moving into more advanced topics.

Section B marks a shift toward deeper conceptual understanding and descriptive answers. Students must attempt any three out of five questions, each carrying 7 marks. The questions in this section require detailed explanations along with circuit diagrams where necessary. The topics include the action of a PN-junction diode under both forward and reverse bias conditions, demonstrating how minority and majority carriers behave and how depletion regions and barriers change. Another question asks students to draw and explain the working of a full-wave bridge rectifier and calculate the Peak Inverse Voltage (PIV). Students are also required to explain the construction, operation, and transfer characteristics of an n-channel EMOSFET, demonstrating their knowledge of MOSFET structures and output behaviors. Additionally, questions in this section include deriving expressions for an op-amp-based integrator and differentiator using appropriate circuit diagrams, and explaining the operation of a Cathode Ray Tube (CRT) along with how unknown voltage and frequency can be measured using a Cathode Ray Oscilloscope (CRO). This section tests whether students can transform theoretical knowledge into clear explanations supported with proper reasoning and diagrams.

The last part of the paper, Section C, consists of long-answer analytical questions divided into multiple sub-sections. In each sub-section (Q3 to Q7), students must attempt one question. These questions require mathematical derivations, in-depth reasoning, circuit analysis, and thorough understanding of device characteristics. The topics covered in this section represent some of the most crucial areas of electronics engineering. Students may be asked to describe, in detail, the transition and diffusion capacitances of a PN-junction diode and derive mathematical expressions for these capacitances. Alternatively, they may be asked to differentiate between Zener breakdown and avalanche breakdown, explaining the physical mechanisms behind each type of breakdown.

Further into Section C, students encounter questions related to Zener diode shunt regulators where they must analyze a practical circuit containing a 25V input supply, a series resistance, and a load resistance, and calculate the resulting load voltage and current. Another question covers the working of a tunnel diode, including its principle of operation, construction, and unique negative-resistance region reflected in its V–I characteristics. Students also face questions requiring DC analysis of a transistor network, calculating the DC levels of IB and Vc from a given circuit diagram printed on Page 2. Other questions focus on explaining the operation, AC equivalent circuit, and deriving expressions for voltage gain (Av), input resistance (Rin), and output resistance (Ro) of a common-source N-channel JFET amplifier, highlighting the importance of small-signal modeling in analog analysis.

The final portion of the paper includes questions on measuring instruments and op-amp imperfections. Students may be asked to calculate the range of output voltage produced by an op-amp circuit shown in Page 3, demonstrating understanding of saturation limits and resistor networks. They may also need to explain important op-amp parameters such as input offset voltage, output offset voltage, input bias current, input offset current, and differential versus common-mode operation. The concluding question options involve drawing and explaining the block diagram of a ramp-type digital voltmeter and describing digital storage oscilloscopes, including their advantages and disadvantages compared to traditional analog oscilloscopes.

Overall, this exam paper is structured to thoroughly evaluate a student's theoretical knowledge, analytical skills, circuit interpretation capability, and practical understanding of electronic instruments. By combining conceptual questions, circuit-based numerical problems, device characteristics, and instrument design, the paper ensures a complete and rigorous assessment of the subject Electronics Engineering.