This is an old revision of the document!

Mesh set

In every closed circuit and every mesh of the network, the sum of all voltages is zero!
Set the voltage on the power supply to $12~\rm V$ and measure this voltage precisely using a multimeter. Set up the measuring circuit shown in figure 1.

Fig. 1: Mesh-set

Add the voltage arrows and measure $U$, $U_{\rm 1}$ und $U_{\rm 2}$:

What is the mesh set here?

Check the formula with the measured values:

The resistors $R_{\rm 1}$ and $R_{\rm 2}$ connected in series form a voltage divider. What is the ratio between the voltages $U_{\rm 1}$ and $R_{\rm 2}$?

$$ \frac{U_1}{U_2} = $$

Set of nodes

At each junction point, the sum of all incoming and outgoing currents is equal to zero!
Set the voltage on the power supply to $12~\rm V$ and measure the voltage accurately with a multimeter. In the first step, set up the measuring circuit shown in figure 2:

Fig. 2: Node-set circuit 1

Draw the arrows for the directions of currents $I_{\rm 1}$ and $I_{\rm 2}$ in figure 3. The DC current measurement range must be set on both multimeter using the rotary switch. Then measure currents $I_{\rm 1}$ and $I_{\rm 2}$ and enter the measured values in table 2.

Fig. 3: Node-set circuit 2

What is the relationship between currents $I_{\rm 1}$ and $I_{\rm 2}$?

$$ \frac{I_1}{I_2} = $$

Switch the power supply back on and measure the current $I$. Enter its value in table 2.

Determine the node set for node K and check its validity.

Using the measured values for resistors $R_{\rm 1}$, $R_{\rm 2}$, and $R_{\rm 3}$, calculate the total resistance $R_{\rm KP}$:

Using the calculated value $R_{\rm KP}$, check the measured value of the total current:
$$ I=\frac{U}{R_{KP}} = $$