The figure below depicts a 0-to-10 potentiometer as a variable load resistor connected to a circuit of an unknown architecture. When the wiper position on the potentiometer was adjusted such that , the current through it was measured to be 3 mA, and when the wiper was lowered so that , the current decreased to 2.5 mA. Determine the value of that would extract maximum power from the circuit.

Respuesta :

Explanation:

circuit can be considered as thevenin's equivalent

The equivalent circuit is

Given,

[tex]\begin{aligned}&I_{L}=3 m A\\&R_{L}=1.2 \mathrm{K} \Omega\end{aligned}[/tex]

By applying KVL to circuit

[tex]\begin{array}{l}I=\frac{V_{th} }{R+h+R_{L}} \\3 m=\frac{V _{th} }{R_{m}(k \Omega)+1.2 K}\end{array}\\[/tex]

[tex]V_{t h}=3 R+h+3 \times 1.2[/tex]

[tex]I=\frac{Vth}{Rth+R_{L}}[/tex]

[tex]2.5 m=\frac{Vth}{Rth(k \Omega)+2 K}[/tex]

[tex]V_{th}=2.5 \mathrm R_{th} +5[/tex]

By equating, we get

[tex]R_{th}=2 \cdot 8 K \Omega[/tex]

According to maximum power transfer theorem, maximum power in transfered to load

[tex]R_{L}=R_{th}[/tex]

[tex]R_{th}=2 \cdot 8 K \Omega[/tex]

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