For an AC voltage controller with RMS output voltage of 230V from a 230V, 50Hz source at 30° firing angle, what is the power factor?

The correct answer is A: 0.87. For AC voltage controller: PF = (1/π)√(π² - 4α²) × sin(2α)/(2α) where α = 30° = π/6. This yields PF ≈ 0.87 with leading reactive current.

The no-load core loss in a transformer is primarily due to:

The correct answer is B: Hysteresis and eddy current losses in core. No-load losses consist of hysteresis loss (due to core magnetization reversal) and eddy current loss (due to induced currents in core material). Copper loss occurs only under load.

The power factor of an AC circuit is defined as:

The correct answer is A: cos(φ) where φ is the phase angle between voltage and current. Power factor is the cosine of the phase angle between voltage and current, representing the fraction of apparent power that is real power.

In a boost converter operating in continuous conduction mode (CCM), the average output voltage relationship is:

The correct answer is B: Vo = Vin / (1 - D). Boost converter output voltage: Vo = Vin / (1 - D), where D is duty cycle. This always produces Vo > Vin for 0 < D < 1.

In a synchronous counter design, what is the primary advantage over asynchronous counters?

The correct answer is B: All flip-flops are clocked simultaneously, eliminating propagation delay issues. Synchronous counters clock all flip-flops at the same time, preventing cumulative propagation delays that cause glitches in asynchronous designs.

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Electrical Engg (EEE)

Electrical machines, power systems, circuits

321 Q 7 Topics Take Mock Test

Difficulty: All Easy Medium Hard 281–290 of 321

Topics in Electrical Engg (EEE)

All Circuit Analysis 100 Electrical Machines 100 Power Systems 100 Control Systems 100 Power Electronics 100 Electrical Measurements 40 Digital Electronics 100

Q.281 Medium Circuit Analysis

A network is said to be bilateral if:

A It contains only two branches

B Its response is same regardless of direction of current flow

C It has two voltage sources

D It contains both resistive and reactive elements

Correct Answer: B. Its response is same regardless of direction of current flow

EXPLANATION

Bilateral networks are linear networks where reciprocal relationships hold. Networks with ideal diodes are unilateral (non-bilateral).

Test

Q.282 Medium Circuit Analysis

In a magnetically coupled circuit with two inductors L₁ and L₂ with mutual inductance M, if current increases in primary, the induced voltage in secondary opposes this change. This demonstrates:

A Lenz's law

B Faraday's law

C Both A and B

D Ampere's law

Correct Answer: C. Both A and B

EXPLANATION

Faraday's law describes EMF generation; Lenz's law describes the direction (opposition to change). Both apply to mutual inductance phenomena.

Test

Q.283 Medium Circuit Analysis

In a circuit with mutual inductance between two coils, the coupling coefficient k is defined as:

A k = M/(L₁+L₂)

B k = M/√(L₁×L₂)

C k = M×L₁×L₂

D k = (L₁-L₂)/M

Correct Answer: B. k = M/√(L₁×L₂)

EXPLANATION

Coupling coefficient k = M/√(L₁L₂), where 0 ≤ k ≤ 1. k=1 indicates perfect coupling, k=0 means no coupling.

Test

Q.284 Medium Circuit Analysis

The Norton equivalent of a network is found by:

A Finding short-circuit current at load terminals and open-circuit impedance

B Finding open-circuit voltage and equivalent resistance with sources deactivated

C Finding short-circuit current and equivalent resistance with sources deactivated

D Only using current sources

Correct Answer: C. Finding short-circuit current and equivalent resistance with sources deactivated

EXPLANATION

Norton equivalent: IN = Isc (short-circuit current) and RN = Rth (equivalent resistance). Norton and Thevenin equivalents are related: Vth = IN × RN

Test

Q.285 Medium Circuit Analysis

In mesh analysis, if a circuit has dependent sources, the approach is:

A Cannot be used for dependent sources

B Apply mesh current method but express dependent source in terms of mesh currents

C Only nodal analysis can be used

D Use superposition only

Correct Answer: B. Apply mesh current method but express dependent source in terms of mesh currents

EXPLANATION

Mesh analysis works with dependent sources by expressing the controlling variable in terms of mesh currents, then solving the resulting equations.

Test

Q.286 Medium Circuit Analysis

In a circuit, the star-delta transformation is used to:

A Reduce circuit complexity and solve it easily

B Convert three-terminal star network to delta and vice versa

C Balance three-phase circuits

D Both A and B

Correct Answer: D. Both A and B

EXPLANATION

Star-delta transformation converts between two three-terminal network configurations, simplifying circuit analysis by eliminating nodes that cannot be solved directly.

Test

Q.287 Medium Circuit Analysis

The reciprocity theorem states that in a linear bilateral network:

A Current is proportional to voltage

B Voltage response at node A due to source at B equals current response at B due to same source at A

C Excitation and response are interchangeable

D All of the above

Correct Answer: C. Excitation and response are interchangeable

EXPLANATION

Reciprocity theorem: If a voltage source at port 1 produces current at port 2, then the same source at port 2 produces equal current at port 1. Applicable for bilateral linear networks.

Test

Q.288 Medium Circuit Analysis

In a planar circuit, the relationship between number of nodes (n), branches (b), and independent loops (m) is:

A m = b - n

B m = b - n + 1

C m = n - b + 1

D m = n + b - 1

Correct Answer: B. m = b - n + 1

EXPLANATION

For a connected planar circuit: Number of independent loops = b - n + 1 (also known as cyclomatic complexity or mesh rank)

Test

Q.289 Medium Circuit Analysis

For maximum power transfer to a load from a source with Thevenin equivalent (Vth, Rth), the load resistance should be:

A Zero

B Infinite

C Equal to Rth

D Equal to Vth

Correct Answer: C. Equal to Rth

EXPLANATION

Maximum power transfer theorem: Load resistance RL should equal Thevenin resistance Rth for maximum power delivery. Maximum power = Vth²/(4Rth)

Test

Q.290 Medium Circuit Analysis

A network has 8 branches and 5 nodes. The number of independent mesh equations required is:

A 3

B 4

C 5

D 8

Correct Answer: B. 4

EXPLANATION

Number of independent mesh equations = b - n + 1, where b=branches, n=nodes. Here: 8 - 5 + 1 = 4

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