# Twoport T-Network - Why does the voltage increase?

I am new to electrical engineering and currently struggling to understand following network: Activating both current sources and using arbitrary values for the currents and for the resistors i get a higher voltage for U_1 and U_2 in comparison to when i only activate one current source.

It just isn't intuitive for me. I imagine to water pumps; why should one pump increase the pressure of the other pump and vice versa?

• Makes sense to me... More current through R_C means more voltage across R_C. Aug 26 '20 at 10:57

A current source has infinite internal resistance. Let's assume all resistors have the same value, 1 $$\\Omega\$$. Let's also assume that $$\I_1=1\text{A}\$$ and $$\I_2\$$ is either zero or equal to $$\I_1\$$.
a) $$\I_2=0\text{A}\$$ means $$\R_B\$$ will be in series with an infinite resitance, and both of them in parallel with $$\R_C\$$. The equivalent resistance will be $$\R_e=1\Omega\$$. The total resistance seen by $$\I_1\$$ will be $$\R_A+R_e=2\Omega\$$, thus the voltage will be $$\U_1=2\Omega\cdot1\text{A}=2\text{V}\$$. An alternative way of looking at this is to consider the current through $$\R_B\$$ as zero, and only $$\1\text{A}\$$ flowing through $$\R_A\$$ and $$\R_C\$$ from $$\I_1\$$.
b) $$\I_2=1\text{A}\$$ means the currents through $$\R_A\$$ and $$\R_B\$$ will be $$\1\text{A}\$$, for each, and for $$\R_C\$$ there will be $$\2\text{A}\$$ (one from each source). Thus the voltages across each resistors will be proportional to the currents, and each side will see a voltage of $$\3\text{V}\$$.