Multiple sources in one network: Do some circuit topologies legitimately require more than one independent voltage or current source?
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ATrue
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BFalse
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COnly in AC systems, never in DC
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DOnly for testing, not for real designs
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EOnly if sources are identical and in series
Answer
Correct Answer: True
Explanation
Introduction / Context:Real systems often combine multiple sources to meet performance needs: biasing and signal injection in amplifiers, dual rails in op-amp circuits, battery + photovoltaic hybrids, or mixed current/voltage excitations in measurement setups.
Given Data / Assumptions:
- Linear or nonlinear networks may include several independent sources.
- Sources can be of different types (voltage or current) and polarities.
- Operation is steady-state for analysis clarity.
Concept / Approach:
Superposition applies to linear networks: the response to multiple independent sources equals the algebraic sum of the responses to each source acting alone (with others deactivated per type). Multiple sources enable bias + signal, redundancy, or energy sharing among subsystems.
Step-by-Step Solution:
Identify the purpose of each source (e.g., DC bias, AC signal, reference, current excitation).Analyze via superposition for linear circuits: zero-out voltage sources to their internal resistance and current sources to their internal resistance.Combine contributions to find voltages/currents of interest.Validate operating points and power flows for safety and performance.Verification / Alternative check:
Common designs—op-amp amplifiers with +V and −V rails, RF mixers with LO + RF sources, LED drivers mixing a current source with voltage-limited supply—demonstrate legitimate multiple-source usage.
Why Other Options Are Wrong:
- DC systems frequently use multiple sources (e.g., dual batteries, bias plus signal).
- Use is not limited to lab testing; it is standard practice in production designs.
- Sources need not be identical nor strictly series-connected; topology depends on the function.
Common Pitfalls:
Failing to check interaction between sources, such as back-driving or circulating currents. Use diodes, OR-ing controllers, or proper isolation as needed.
Final Answer:
True