PHYS 1422 211 1310
FALL 2012/2013
Sec: 211
Hind Alsayyar
200800890
Lab report
Kirchhoff's Laws
Kirchhoff's Laws
Purpose:
The purpose of this lab activity is to study Kirchhoff's voltage law and Kirchhoff's
current law by making voltage and current measurement between various points in an
electric circuit.
Kirchhoff's laws for voltage and current:
Kirchhoff's voltage laws
The sum of the voltage around any close loop is equal to zero.
-
VP +V1+V2+V3=0
Kirchhoff's current laws
The current going into a junction or node is equal to the current going out of a node.
Ip-I1-I2-I3=0 ;
=
Ip =I1+I2+I3
Kirchhoff's Laws
Required equipment and supplies:
Resistors, power supplies, amp meter, voltmeter and cables.
Procedure:
Part 1
1-Measure the actual values of these resistors.
2- Measure the actual power supply voltage.
3- Measure the voltage V1, V2 and V3.
4- Record these values in tables below.
I=0.042A
Resistor
R value
R1
50
R2
70
R3
100
Voltage
V1
V2
V3
Vp
Measured voltage
2.2 v
2.9 v
4.2 v
9.3 v
Calculated voltage
50*0.042= 2.1
70*0.042= 2.94
100*0.042= 4.2
9.24 v
Percentage of Error
%DI f f = | theoretical value- experimental value/theoretical value|%
Error in %
0.0455%
0.0138%
0%
0.0065%
Kirchhoff's Laws
Part 2
Kirchhoff’s current law
1-Measure the actual values of these resistors.
2- Measure the actual power supply voltage.
3- Measure the voltage V1, V2 and V3 across each resistor.
4-Don’t measure Ip,Ia,Ib or Ic yet.
Current
I1
I2
I3
Ip
Resistor
R value
R1
50
R2
70
R3
100
Resistor
Voltage
R1
10 v
Calculate
voltage
10 v
R2
10 v
10 v
R3
10 v
10 v
Measured current
0.19A
0.14A
0.1A
0.43 A
Calculate current
10/50= 0.2
10/70=0.14
10/100=0.1
0.44