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100+ Free ISRO Scientist Electrical Practice Questions

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2026 Statistics

Key Facts: ISRO Scientist Electrical Exam

80 + 15 MCQs

Part A (Core) + Part B (Aptitude) questions

ISRO recruitment notification

120 Min

Total duration for 95 questions

ISRO recruitment notification

-1/3 mark

Negative marking on assigned question marks

ISRO recruitment notification

₹750

Application fee (with refunds for appearing candidates)

ISRO recruitment notification

80 / 20

Practice bank split: Core / Aptitude (of 100 free MCQs)

OpenExamPrep blueprint

ISRO Scientist Electrical exam comprises 95 MCQs (80 Core + 15 Aptitude) over 120 minutes. Negative marking is -1/3. Application fee is ₹750, with refunds based on category and attendance.

Sample ISRO Scientist Electrical Practice Questions

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

1A star network has three equal resistors of 9 Ω each. What is the value of the equivalent resistors in the delta network?
A.3 Ω
B.9 Ω
C.27 Ω
D.81 Ω
Explanation: In a star-delta transformation, if all resistors in the star network are equal to R_y, then each resistor in the delta network (R_d) is equal to 3 * R_y. Thus, R_d = 3 * 9 = 27 Ω.
2A series RC circuit with R = 10 kΩ and C = 100 μF is connected to a 10 V DC supply at t = 0. What is the voltage across the capacitor at t = 1 second?
A.3.68 V
B.5.00 V
C.6.32 V
D.10.00 V
Explanation: The time constant of the circuit is τ = R * C = 10,000 * 100 * 10^-6 = 1 second. The voltage across the capacitor in a charging series RC circuit is given by v_c(t) = V_s * (1 - e^(-t/τ)). At t = 1 s (t = τ), v_c(1) = 10 * (1 - e^-1) = 10 * (1 - 0.368) = 6.32 V.
3An AC voltage v(t) = 100 cos(314t + 30°) V is applied to a load, resulting in a current i(t) = 5 cos(314t - 30°) A. What are the active power and power factor of the load?
A.250 W, 0.5 lagging
B.250 W, 0.5 leading
C.125 W, 0.5 lagging
D.125 W, 0.866 leading
Explanation: Active power P = V_rms * I_rms * cos(θ) = (100/√2) * (5/√2) * cos(60°) = 250 * 0.5 = 125 W. The phase difference is θ = θ_v - θ_i = 30° - (-30°) = 60°, meaning the current lags the voltage by 60°, resulting in a power factor of cos(60°) = 0.5 lagging.
4A parallel RLC circuit has R = 3.16 kΩ, L = 10 mH, and C = 0.1 μF. What are the resonant frequency (ω_0) and quality factor (Q) of this circuit?
A.10,000 rad/s, 100
B.31,622 rad/s, 100
C.31,622 rad/s, 10
D.10,000 rad/s, 10
Explanation: The resonant frequency is ω_0 = 1 / √(L·C) = 1 / √(10×10^-3 × 0.1×10^-6) = 1 / √(10^-9) = 31,622 rad/s. For a parallel RLC circuit the quality factor is Q = R·√(C/L) = 3,160 × √(0.1×10^-6 / 10×10^-3) = 3,160 × √(10^-5) ≈ 10. Equivalently, Q = R / (ω_0·L) = 3,160 / (31,622 × 10×10^-3) ≈ 10, confirming the pair 31,622 rad/s and Q = 10.
5For a two-port network, the impedance parameters are Z_11 = 4 Ω, Z_12 = Z_21 = 2 Ω, and Z_22 = 3 Ω. What is the transmission parameter A of the network?
A.1.5
B.2.0
C.0.5
D.1.0
Explanation: The relationship between Z-parameters and ABCD transmission parameters is given by: A = Z_11 / Z_21. Substituting the given values, A = 4 / 2 = 2.0 (dimensionless).
6A load resistance R_L is connected across a source network with a dependent source. The Open-circuit voltage across the terminals is V_oc = 20 V, and the Short-circuit current is I_sc = 5 A. What is the value of R_L for transferring maximum power to the load, and what is the maximum power transferred?
A.4 Ω, 100 W
B.4 Ω, 25 W
C.2 Ω, 50 W
D.8 Ω, 12.5 W
Explanation: According to the Maximum Power Transfer Theorem, maximum power is transferred when the load resistance R_L equals the Thevenin equivalent resistance R_th of the source. Here, R_th = V_oc / I_sc = 20 / 5 = 4 Ω. The maximum power transferred to R_L is P_max = V_oc^2 / (4 * R_th) = 20^2 / (4 * 4) = 400 / 16 = 25 W.
7A series RLC circuit has R = 20 Ω, L = 0.1 H, and C = 100 μF. The circuit is excited by a step voltage source at t = 0. The response of the circuit is:
A.Critically damped
B.Underdamped
C.Overdamped
D.Undamped
Explanation: The damping ratio (ζ) of a series RLC circuit is given by ζ = (R / 2) * √(C / L). Substituting the values: ζ = (20 / 2) * √(100 * 10^-6 / 0.1) = 10 * √(10^-3) = 10 * 0.03162 = 0.3162. Since ζ < 1, the system is underdamped.
8Two coupled coils with self-inductances L_1 = 4 mH and L_2 = 9 mH have a coupling coefficient k = 0.5. What is the mutual inductance M between the two coils?
A.6.0 mH
B.3.0 mH
C.2.25 mH
D.1.5 mH
Explanation: The mutual inductance M is given by the formula M = k * √(L_1 * L_2). Substituting the values: M = 0.5 * √(4 * 9) = 0.5 * √36 = 0.5 * 6 = 3.0 mH.
9A sphere of radius R carries a uniform volume charge density ρ. Using Gauss's Law, what is the electric field intensity E at a distance r (where r < R) from the center of the sphere?
A.ρ * r / (3 * ε)
B.ρ * R^3 / (3 * ε * r^2)
C.ρ * r^2 / (3 * ε * R)
D.Zero
Explanation: Applying Gauss's Law for a spherical surface of radius r < R: closed integral of E * dA = Q_enclosed / ε. Here, E * (4 * π * r^2) = (ρ * 4/3 * π * r^3) / ε. Solving for E gives E = ρ * r / (3 * ε).
10In a lossy dielectric medium with conductivity σ and permittivity ε, an AC electric field E = E_0 * sin(ωt) is applied. What is the ratio of the magnitude of conduction current density to displacement current density?
A.σ / (ω * ε)
B.ω * ε / σ
C.σ * ω * ε
D.Zero
Explanation: Conduction current density is J_c = σ * E. Displacement current density is J_d = ∂D/∂t = ε * ∂E/∂t. For E = E_0 * sin(ωt), J_c = σ * E_0 * sin(ωt) and J_d = ε * ω * E_0 * cos(ωt). The ratio of their magnitudes is |J_c| / |J_d| = σ / (ω * ε). This ratio is also known as the loss tangent (tan δ).

About the ISRO Scientist Electrical Exam

The Indian Space Research Organisation (ISRO) Scientist/Engineer SC Electrical recruitment exam consists of two parts. Part A contains 80 discipline-specific multiple-choice questions focusing on core electrical engineering subjects: Electric Circuits, Electromagnetic Fields, Signals and Systems, Electrical Machines, Power Systems, Control Systems, Electrical and Electronic Measurements, Analog and Digital Electronics, and Power Electronics. Part B contains 15 general aptitude questions covering quantitative aptitude, logical reasoning, and numerical ability. The total test time is 120 minutes, with a negative marking of one-third (-1/3) of the question's value for each incorrect answer.

Assessment

The written test comprises Part A (80 Core MCQs, 100 marks) and Part B (15 Aptitude MCQs, 20 marks). The duration is 120 minutes. There is a negative marking of one-third (-1/3) of the marks allocated for each wrong answer. Candidates must qualify both parts individually.

Time Limit

120 minutes

Passing Score

50% individually in Part A and Part B (General), 40% individually in Part A and Part B (Reserved)

Exam Fee

INR 750 (refundable to ₹250 or ₹0 depending on candidate category and attendance) (Indian Space Research Organisation (ISRO))

ISRO Scientist Electrical Exam Content Outline

10%

Electric Circuits

Network theorems, transient response, AC steady-state analysis, resonance, and two-port networks

10%

Electromagnetic Fields

Gauss's Law, Ampere's Law, Maxwell's equations, boundary conditions, and wave propagation

10%

Signals and Systems

LTI systems, Fourier series & transforms, Laplace transform, z-transform, and sampling theorem

15%

Electrical Machines

Transformers, DC machines, three-phase induction motors, and synchronous machines

15%

Power Systems

Transmission line performance, fault analysis, system stability, load flow, and protection

10%

Control Systems

Mathematical modeling, root locus, Bode/Nyquist plots, compensators, and state-space analysis

5%

Electrical & Electronic Measurements

PMMC, moving iron, bridge measurements, instrument transformers, and digital voltmeters

10%

Analog & Digital Electronics

Diode/transistor circuits, Op-Amps, logic gates, Boolean algebra, and sequential circuits

15%

Power Electronics

SCR/IGBT characteristics, phase rectifiers, DC-DC converters, inverters, and PWM techniques

How to Pass the ISRO Scientist Electrical Exam

What You Need to Know

  • Passing score: 50% individually in Part A and Part B (General), 40% individually in Part A and Part B (Reserved)
  • Assessment: The written test comprises Part A (80 Core MCQs, 100 marks) and Part B (15 Aptitude MCQs, 20 marks). The duration is 120 minutes. There is a negative marking of one-third (-1/3) of the marks allocated for each wrong answer. Candidates must qualify both parts individually.
  • Time limit: 120 minutes
  • Exam fee: INR 750 (refundable to ₹250 or ₹0 depending on candidate category and attendance)

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 Electrical Study Tips from Top Performers

1Focus heavily on numerical problem-solving. ISRO questions often require quick calculations without a calculator.
2Strengthen core concepts of Electric Machines, Power Electronics, and Power Systems as they carry high weight.
3Practice previous years' ISRO and GATE questions to understand the difficulty level and typical question models.
4Don't neglect Part B (Aptitude). Scoring high in aptitude is crucial as it has a separate qualifying cutoff.
5Work on time management. Solving 95 questions in 120 minutes requires speed and accuracy.

Frequently Asked Questions

What is the exam pattern for ISRO Scientist/Engineer SC Electrical?

The written exam is a pen-and-paper OMR test of 120 minutes. It has two parts: Part A consists of 80 core electrical engineering MCQs (100 marks), and Part B consists of 15 general aptitude MCQs (20 marks), totaling 95 questions.

Is there negative marking in the ISRO Electrical exam?

Yes, there is negative marking. For each incorrect answer, one-third (1/3) of the marks allocated to that question will be deducted.

What is the application fee for ISRO Scientist/Engineer SC?

The application fee is ₹750. However, female, SC, ST, PwBD, and ex-servicemen candidates receive a full refund of ₹750 if they appear for the exam. Other candidates who appear receive a refund of ₹250, making their net fee ₹500.

What are the qualifying marks for the ISRO Electrical written test?

General category candidates must score at least 50% in Part A and 50% in Part B individually. Reserved category candidates must score at least 40% in Part A and 40% in Part B individually.

What is the educational eligibility for ISRO Scientist Electrical?

Candidates must have a first-class B.E./B.Tech or equivalent degree in Electrical Engineering with an aggregate minimum of 65% marks or a CGPA of 6.84 out of 10.