The Thevenin equivalent resistance (Rth) is found by:
Answer: D
Rth is calculated by deactivating all independent sources (short voltage sources, open current sources) and finding equivalent resistance seen from load terminals.
Q.62Easy
In a bridge circuit at balance condition, the product of opposite resistances are equal. This principle is known as:
Answer: C
At Wheatstone bridge balance: R₁/R₂ = R₄/R₃ or R₁×R₃ = R₂×R₄. No current flows through galvanometer.
Q.63Medium
A network has 8 branches and 5 nodes. The number of independent mesh equations required is:
Answer: B
Number of independent mesh equations = b - n + 1, where b=branches, n=nodes. Here: 8 - 5 + 1 = 4
Q.64Medium
For maximum power transfer to a load from a source with Thevenin equivalent (Vth, Rth), the load resistance should be:
Answer: C
Maximum power transfer theorem: Load resistance RL should equal Thevenin resistance Rth for maximum power delivery. Maximum power = Vth²/(4Rth)
Q.65Medium
In a planar circuit, the relationship between number of nodes (n), branches (b), and independent loops (m) is:
Answer: B
For a connected planar circuit: Number of independent loops = b - n + 1 (also known as cyclomatic complexity or mesh rank)
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Q.66Easy
A circuit has three meshes. Using mesh current analysis, the total number of mesh current variables are:
Answer: B
Number of mesh current variables equals the number of independent meshes in the circuit. For 3 independent meshes, we have 3 mesh currents (I₁, I₂, I₃).
Q.67Medium
The reciprocity theorem states that in a linear bilateral network:
Answer: C
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.
Q.68Medium
In a circuit, the star-delta transformation is used to:
Answer: D
Star-delta transformation converts between two three-terminal network configurations, simplifying circuit analysis by eliminating nodes that cannot be solved directly.
Q.69Hard
For a passive linear network, the input impedance looking into terminals is Z(s). If a unit impulse is applied as input, the impulse response h(t) is the:
Answer: C
Impulse response h(t) = L⁻¹[Y(s)] where Y(s) is admittance. For impedance Z(s), admittance Y(s) = 1/Z(s).
Q.70Medium
In mesh analysis, if a circuit has dependent sources, the approach is:
Answer: B
Mesh analysis works with dependent sources by expressing the controlling variable in terms of mesh currents, then solving the resulting equations.
Q.71Medium
The Norton equivalent of a network is found by:
Answer: C
Norton equivalent: IN = Isc (short-circuit current) and RN = Rth (equivalent resistance). Norton and Thevenin equivalents are related: Vth = IN × RN
Q.72Hard
For a two-port network, when port 2 is open-circuited (I₂=0), the parameter measured is:
Answer: A
In hybrid (h) parameters: h₁₁ is input impedance with output open (I₂=0). h₁₁ = V₁/I₁|I₂=₀ measured in ohms.
Q.73Medium
In a circuit with mutual inductance between two coils, the coupling coefficient k is defined as:
Answer: B
Coupling coefficient k = M/√(L₁L₂), where 0 ≤ k ≤ 1. k=1 indicates perfect coupling, k=0 means no coupling.
Q.74Hard
The cut-set matrix is used in circuit analysis to:
Answer: B
Cut-set matrix provides a systematic way to write KVL equations for fundamental cut-sets, an alternative to mesh analysis.
Q.75Easy
A circuit element is said to be active if it:
Answer: B
Active elements (voltage/current sources) can supply power. Passive elements (R, L, C) can only dissipate or store energy.
Q.76Easy
For a network containing resistances and a single voltage source, if we open-circuit the source terminal, the circuit becomes:
Answer: B
Removing all independent sources leaves only passive elements (resistors), making the network passive with no energy supply capability.
Q.77Medium
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:
Answer: C
Faraday's law describes EMF generation; Lenz's law describes the direction (opposition to change). Both apply to mutual inductance phenomena.
Q.78Medium
A network is said to be bilateral if:
Answer: B
Bilateral networks are linear networks where reciprocal relationships hold. Networks with ideal diodes are unilateral (non-bilateral).
Q.79Easy
In nodal analysis, the number of independent equations required to solve a circuit with 'n' nodes (excluding the reference node) is:
Answer: A
In nodal analysis, we need (n-1) independent KCL equations for n nodes, where one node is taken as reference (ground). This follows from the fact that one equation is dependent on others.
Q.80Easy
A voltage source of 10V with internal resistance 2Ω is connected to a load resistance of 8Ω. The maximum power transfer to the load occurs when load resistance is:
Answer: A
Maximum power transfer theorem states that maximum power is transferred when load resistance equals the Thevenin equivalent resistance of the source (2Ω in this case).
