(SEM 1) THEORY EXAMINATION 2017-18 BASIC ELECTRONICS

This is a complete Electronics Engineering (Basic Electronics / EDC / Network & Devices) question paper built according to a 70-mark university pattern. The paper thoroughly covers diodes, rectifiers, BJT characteristics, FET, MOSFET, operational amplifiers, modulation, communication systems, measuring instruments, and DVM/CRO concepts.

The question paper is divided into three sections – A, B, and C, covering short conceptual questions, medium descriptive questions, and long analytical/numerical questions. Ideal for B.Tech 1st year ECE, CSE, IT, EE, EI, and related disciplines.

It is highly useful for semester exam practice, sessional exams, competitive exams, and last-minute revision.

 SECTION A – Short Answer Questions (7 × 2 = 14 Marks)

This section checks basic concepts in analog electronics and communication engineering:

Output voltage of an op-amp with differential input

Ripple factor for rectifiers

Why BJT is a current-controlled device

Advantages of digital instruments over analog

Ideal characteristics of an operational amplifier

Modulation index and AM spectrum

Definition & formula of FET transconductance

These short questions help revise fundamental definitions and formulas.

SECTION B – Descriptive Questions (Attempt Any 3 × 7 = 21 Marks)

Diode Circuits

Full-wave voltage doubler

Bridge rectifier with working

BJT Characteristics

Common emitter configuration with input/output characteristics

Explanation of active, cutoff, and saturation regions

Operational Amplifiers

Op-amp as:

Integrator

Inverting summer

Voltage follower

Digital Multimeter (DMM)

Block diagram + measurement of AC, DC, and other electrical parameters

Communication System

Basic block diagram of communication system

Power saving when one sideband + carrier is suppressed (SSB-SC) with m = 1

These questions develop understanding of active devices and analog circuits.

SECTION C – Long Questions (7 Marks Each)

Q3 – Zener Diode / Special Diodes

Choose one:

Option 1

Determine Vi range for zener conduction

Find Vo for a given diode-regulated circuit

Option 2

Explain Tunnel diode

Explain diffusion and transition capacitance

Q4 – BJT Biasing / FET & MOSFET

Choose one:

Option 1

For a transistor network:

Determine RB and RE

Calculate VB, VCE, VBC

Option 2

Construction, working, characteristics of N-channel JFET

Transfer curve

Construction & working of depletion MOSFET

Q5 – Op-Amp Characteristics / Gain Derivation

Choose one:

Option 1

Determine output voltage of op-amp circuit

Explain:

CMRR

Slew rate

Option 2

Derive voltage gain for:

Inverting op-amp

Non-inverting op-amp

Q6 – Electronic Instruments

Choose one:

Option 1

Block diagram + working of Ramp-Type Digital Voltmeter (DVM)

Option 2

Block diagram of CRO with explanation

Lissajous figure frequency calculation (Given: tangents = 5 vertical, 6 horizontal, fₕ = 1800 Hz → find fᵥ)

Q7 – Amplitude Modulation

Choose one:

Option 1

Define AM

Derive full expression of AM wave

Derive modulation index

Option 2

Calculate modulation index from transmitted power values

With second modulating signal (m = 0.4), calculate new total radiated power