Network Theory

Concept: Thevenin’s Theorem states that any linear electrical network can be replaced by an equivalent circuit consisting of a single voltage source (Thevenin voltage) in series with a resistance (Thevenin resistance).
Step 1: Understanding Thevenin voltage.
The Thevenin equivalent voltage ( ) is defined as the voltage measured across the output terminals when no load is connected.
Step 2: Open-circuit condition.
When the circuit is open (no load connected), no current flows, and the voltage across the terminals is called the open-circuit voltage.
Step 3: Relation to Thevenin voltage.

Step 4: Eliminating other options.

• Short-circuit current: Used to find Norton equivalent
• Load voltage: Depends on load, not open circuit
• Internal resistance: Refers to

Step 5: Conclusion.
Thus, Thevenin equivalent voltage is the open-circuit voltage.

Concept: Maximum power transfer occurs when the load impedance is properly matched with the source impedance.
Step 1: Condition for maximum power (AC circuits).
For complex loads: (i.e., load impedance is the complex conjugate of source impedance)
Step 2: Relevant theorem.
This condition is derived from the Maximum Power Transfer Theorem.
Step 3: Importance.

• Used in communication systems
• Ensures efficient power delivery

Step 4: Eliminating other options.

• Thevenin/Norton: Simplify circuits
• Superposition: Analyzes multiple sources

Step 5: Conclusion.
Thus, Maximum Power Transfer Theorem is used.

Concept: In a resonant circuit, the Quality factor (Q-factor) indicates how sharp or selective the resonance is. It relates the resonant frequency to the bandwidth.
Step 1: Understanding Q-factor.
Q-factor is defined as the ratio of resonant frequency ( ) to the bandwidth (BW).
Step 2: Mathematical relation.

Step 3: Interpretation.

• High Q → Narrow bandwidth → Sharp resonance
• Low Q → Wide bandwidth → Broad response

Step 4: Conclusion.
Thus, Q-factor is inversely proportional to bandwidth.