100+ Free ISRO Scientist/Engineer SC (Electronics) Practice Questions

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Sample ISRO Scientist/Engineer SC (Electronics) Practice Questions

Try these sample questions to test your ISRO Scientist/Engineer SC (Electronics) exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In a series RLC circuit at resonance, the impedance is:

A.Minimum and purely resistive

B.Maximum and purely inductive

C.Zero

D.Purely capacitive

Explanation: At resonance, inductive reactance XL equals capacitive reactance XC, so they cancel. The circuit reduces to R only, giving minimum impedance equal to the resistance.

2Thevenin equivalent voltage Vth across terminals of a linear network is:

A.Short-circuit current times Rth

B.Open-circuit voltage at the terminals

C.Voltage across the load resistor

D.Sum of all internal source voltages

Explanation: Thevenin voltage is defined as the open-circuit voltage between the two terminals after the load is removed. Rth is found from the equivalent resistance with independent sources deactivated.

3For a reciprocal two-port network, which condition holds for the ABCD (transmission) parameters?

A.ZY = 1 for all ports

B.AB − CD = 1

C.AD − BC = 1

D.h11 h22 − h12 h21 = 0 always

Explanation: For a reciprocal two-port, the transmission (ABCD) matrix satisfies AD − BC = 1. This reciprocity condition links cascade parameters of passive reciprocal networks.

4A coil of resistance 10 Ω and inductance 0.1 H is connected to 230 V, 50 Hz supply. The power factor of the circuit is approximately:

A.1.00

B.0.95

C.0.60

D.0.30

Explanation: XL = 2πfL = 2π × 50 × 0.1 ≈ 31.4 Ω. |Z| = √(10² + 31.4²) ≈ 33 Ω. Power factor = R/|Z| = 10/33 ≈ 0.30.

5In a balanced three-phase star-connected load, the line voltage is 400 V. The phase voltage is:

A.230 V

B.400 V

C.346 V

D.693 V

Explanation: For a star connection, Vphase = Vline / √3 = 400 / 1.732 ≈ 230 V. Line current equals phase current in star.

6The quality factor Q of a series RLC circuit at resonance is given by:

A.R / (ω₀ L)

B.ω₀ L / R

C.ω₀ C / R

D.R / (ω₀ C)

Explanation: For a series RLC circuit, Q = ω₀L/R = 1/(ω₀CR) = (1/R)√(L/C). It measures resonance sharpness (energy stored vs energy dissipated per cycle).

7Maximum power transfer to a purely resistive load RL from a linear DC Thevenin source (Vth, Rth) occurs when:

A.RL = Rth/2

B.RL = 2 Rth

C.RL = Rth

D.RL = 0

Explanation: For a resistive DC network, maximum load power occurs at RL = Rth (efficiency 50% at that point). AC networks with reactance require conjugate matching.

8A capacitor of 10 μF is charged to 100 V. The energy stored is:

A.1 J

B.100 mJ

C.500 mJ

D.50 mJ

Explanation: Energy W = ½CV² = 0.5 × 10×10⁻⁶ × 100² = 0.5 × 10⁻⁵ × 10⁴ = 0.05 J = 50 mJ.

9In a π-filter used for power supply smoothing, the component placed across the load is typically:

A.Shunt capacitor

B.Series inductor only

C.Series resistor

D.Shunt inductor only

Explanation: A π-filter has shunt capacitors at input and output with a series inductor between them. The output shunt capacitor bypasses ripple to ground, smoothing the DC.

10For a network function H(s) = 1/(s² + 2ζωₙs + ωₙ²), critical damping occurs when ζ equals:

A.0

B.1

C.0.5

D.2

Explanation: The standard second-order system has poles at −ζωₙ ± ωₙ√(ζ²−1). Critical damping corresponds to ζ = 1 (repeated real poles). ζ < 1 is underdamped; ζ > 1 is overdamped.

About the ISRO Scientist/Engineer SC (Electronics) Exam

The ISRO Scientist/Engineer 'SC' Electronics written test recruits B.E./B.Tech. graduates into India's space programme. The exam tests core ECE knowledge at undergraduate depth plus aptitude, followed by a technical interview. Successful candidates join ISRO centres as Scientist/Engineer 'SC' working on satellites, launch vehicles, and ground systems.

Assessment

Two-stage selection per ICRB Scientist/Engineer 'SC' recruitment: (1) Written test — 95 objective MCQs totalling 100 marks in 120 minutes with Part A core electronics (80 questions, +1 correct, −1/3 wrong) and Part B aptitude (15 questions, 20 marks, no negative marking); (2) Personal interview for candidates shortlisted in approximately 1:5 ratio. Appointed as Scientist/Engineer 'SC' on Level 10 (7th CPC pay matrix).

Time Limit

120 minutes

Passing Score

No fixed qualifying mark published; written-test cutoffs are announced discipline-wise after the exam for interview shortlisting

Exam Fee

₹750 processing fee per application (includes ₹250 non-refundable application fee); partial or full refund on appearing per category rules in the active notification (ISRO Centralised Recruitment Board (ICRB))

ISRO Scientist/Engineer SC (Electronics) Exam Content Outline

10%

Network Theory

AC circuits, resonance, Thevenin/Norton, two-port parameters, three-phase systems, filters

10%

Electronic Devices

Semiconductor physics, PN junction, BJT, MOSFET, optoelectronics, fabrication basics

10%

Analog Electronics

Op-amps, amplifiers, oscillators, active filters, ADC/DAC, precision rectifiers

10%

Digital Electronics

Boolean algebra, combinational/sequential circuits, counters, memory, logic families, 8085 basics

10%

Control Systems

Transfer functions, stability, Routh-Hurwitz, Bode/Nyquist, root locus, PID, state-space

10%

Communication Systems

Sampling, AM/FM, PCM, digital modulation, Shannon capacity, coding, receivers

Electromagnetics

Maxwell's equations, plane waves, transmission lines, waveguides, antennas, link budget

12%

Signals, Systems & Engineering Math

Laplace/Fourier/Z-transforms, LTI systems, convolution, probability, linear algebra, ODEs

20%

General Aptitude

Quantitative aptitude, logical reasoning, verbal ability, general awareness including ISRO/space context

How to Pass the ISRO Scientist/Engineer SC (Electronics) Exam

What You Need to Know

Passing score: No fixed qualifying mark published; written-test cutoffs are announced discipline-wise after the exam for interview shortlisting
Assessment: Two-stage selection per ICRB Scientist/Engineer 'SC' recruitment: (1) Written test — 95 objective MCQs totalling 100 marks in 120 minutes with Part A core electronics (80 questions, +1 correct, −1/3 wrong) and Part B aptitude (15 questions, 20 marks, no negative marking); (2) Personal interview for candidates shortlisted in approximately 1:5 ratio. Appointed as Scientist/Engineer 'SC' on Level 10 (7th CPC pay matrix).
Time limit: 120 minutes
Exam fee: ₹750 processing fee per application (includes ₹250 non-refundable application fee); partial or full refund on appearing per category rules in the active notification

Keys to Passing

Complete 500+ practice questions
Score 80%+ consistently before scheduling
Focus on highest-weighted sections
Use our AI tutor for tough concepts

ISRO Scientist/Engineer SC (Electronics) Study Tips from Top Performers

1Revise GATE EC-level topics — ISRO electronics papers heavily overlap with networks, devices, analog/digital, communications, control, and electromagnetics.

2Practice timed mocks at ~95–100 questions in 120 minutes; manage negative marking in Part A (−1/3) by skipping uncertain items.

3Part B aptitude has no negative marking — attempt all aptitude items after finishing Part A practice.

4Solve official previous-year ICRB electronics papers posted on isro.gov.in under the active recruitment advertisement.

Frequently Asked Questions

What is the ISRO Scientist/Engineer SC Electronics exam pattern?

Per ICRB Scientist/Engineer 'SC' pattern (confirm in the live advertisement), the written test has 95 MCQs totalling 100 marks in 120 minutes. Part A has 80 discipline-specific questions with +1 mark for correct and −1/3 for wrong answers. Part B has 15 aptitude MCQs worth 20 marks total with no negative marking.

What is the ISRO ICRB application fee?

All candidates pay ₹750 per application (including a ₹250 non-refundable application fee). Women, SC/ST, and PwBD candidates receive a full ₹750 refund on appearing; male General/OBC candidates receive ₹500 back on appearing, per the official FAQ.

Is there a published passing score for the ISRO written test?

ISRO does not publish a fixed qualifying percentage in advance. Discipline-wise cutoffs are set after the exam based on performance and vacancy, and candidates are shortlisted for interview in approximately a 1:5 ratio.

How does this practice bank match the real exam?

This bank provides 80 ECE core questions and 20 aptitude items to mirror the official 80:20 technical-to-aptitude split. Topics align with undergraduate ECE syllabus and previous ICRB electronics papers; drill official previous-year papers on isro.gov.in for exact style.