For finding Thevenin equivalent circuit, the Circuit Current Sources have been replaced by:
infinite resistance
To determine the Thevenin equivalent circuit of a linear electrical network, a standard procedure involves simplifying the circuit by deactivating all independent sources.
Thevenin Equivalent Circuit Analysis
Thevenin's theorem states that any linear electrical network can be replaced by an equivalent circuit consisting of a single voltage source ($V_{th}$) in series with an impedance or resistance ($R_{th}$). This simplification is particularly useful for analyzing the behavior of a specific part of a larger circuit.
Deactivating Independent Sources
A crucial step in finding the Thevenin equivalent resistance ($R_{th}$) is to deactivate the independent sources within the original circuit:
- Independent Voltage Sources: These are replaced by a short circuit, which has zero resistance ($0 \, \Omega$). This is because an ideal voltage source maintains a constant voltage regardless of the current flowing through it; effectively, its internal resistance is zero.
- Independent Current Sources: These are replaced by an open circuit, which represents infinite resistance ($\infty \, \Omega$). An ideal current source supplies a constant current irrespective of the voltage across it; hence, it acts as an infinite resistance path when deactivated.
Dependent sources, on the other hand, are usually not deactivated but are left in the circuit while calculating $R_{th}$.
Replacing Current Sources
The question specifically asks how independent current sources are replaced when finding the Thevenin equivalent. Based on the principle of deactivating sources:
- Independent current sources are replaced by an open circuit.
- An open circuit offers infinite resistance to the flow of current.
Therefore, for finding the Thevenin equivalent circuit, current sources are replaced by infinite resistance.
Important Questions from Thevenin's Theorem
- Which linear circuit can be used as an equivalent circuit for a single voltage source and a series resistance ?
Which theorem is advantageous, when we have to determine the current in a particular element of a linear bilateral network particularly when it is desired to find the current which flows through a resistor for its different values?
Which of the following theorem states that "a linear two-terminal circuit can be replaced by an equivalent circuit consisting of a voltage source VTH in series with a resistor RTH", where VTH is the open circuit voltage at the terminals and RTH is the input or equivalent resistance at the terminals, when the independent sources are turned off
Which of the theorem does provide a mathematical technique for replacing a given network, as viewed from two output terminals, by a single voltage source with a series resistance?
Thevenin's Theorem states that, any linear active Double terminal network containing voltage and resistance sources can be replaced by a ________ Voltage source in _______ with ________ resistance.
