Practice Part 1
Equipment:
 Breadboard
 DC Power Supply with timeconstant EMF (0 to 25.0V DC)
 Three resistors with: and one variable resistor,
 Two universal instruments.
Procedure:
Connect the circuit as it shown in Figure 4.
Experimental determination of equivalent Thevenin generator
1) Disconnect the ammeter and variable resistance R_{L}. Set up the voltage on 20 V.
2) Connect the voltmeter between terminals A and B and measure the Thevenin voltage generator
3) Connect the ammeter and measure the current of short circuit between
terminals A and B with (R_{L}=0)
4) Calculate the equivalent resistance ( R_{L}=0 – short circuit on terminals A
and B).
Experimental determination of the current I_{L }and the power P_{L} for the resistor R_{L}
5) Connect again the circuit shown in Figure 4. Set up and keep the voltage at 20V. Changing the resistance of the variable resistor R_{L }for the values in Table 1 measure and record the values of current I_{L }through resistor R_{L }and the voltage U_{L} across the resistor R_{L}.
Table 1

Measured 
Measured 
Calculated 
Resistance R_{l} (k?) 
Current I_{l} (mA) 
Voltage(V) U_{l}=R_{l} I_{l} 
Power (W) P_{l}= U_{l} I_{l} 
0 



2 



4 



_{6} 



_{8} 



R_{T} 



? 



6) From the data in Table 1 draw graphs for the U_{L}=f (I_{L}) and P_{L}=f (R_{L})
and one variable resistor
Two universal instruments
Procedure:
7) In Figure 5 is shown equivalent Thevenin circuit. Connect the component of the circuit and set the voltage of the source at the equivalent Thevenin voltageE_{T} calculated in Theory Part 1.
8) Connect one of the multimeters as a voltmeter across the source and the other as ammeter between the resistors R4=R_{T }and R_{L}.
9) Changing the resistance of the resistor R_{L }for the values in Table 2 measure and record the values of currentI_{L }through resistor R_{L }and the voltage UL across the resistorR_{L}.
10) Calculate and record the power on the resistor R_{L }for the values from Table 2.
Table 2

Measured 
Measured 
Calculated 
Resistance R_{l} (k?) 
Current I_{l} (mA) 
Voltage(V) U_{l}=R_{l} I_{l} 
Power (W) P_{l}= U_{l} I_{l} 
0 



2 



4 



_{6} 



_{8} 



R_{T} 



? 



11) From the data in Table 2 draw graph for the U_{L}=f (I_{L}) and P_{L}=f (R_{L}).
12) What we can conclude from the results?