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Physics for Engineers PHYS 1422
Lab 5: Kirchhoff’s Laws
Kowther Al-Musallam
201001935
Lab Report 3
Objective:
Our objective is to study Kirchhoff’s Law and it’s current law by making voltage and current
measurements between various points in an electric circuit.
Kirchhoff’s voltage law (KVL):
Kirchhoff’s Current law (KCL):
𝐼𝑖𝑛 = 𝐼𝑂𝑢𝑡
Required equipment:
Resistors, power supplies, amp meter, voltmeter, cables.
Procedure:
Part I: Kirchhoff’s voltage law:
Build the circuit using Vp=10 v
1.
2.
3.
4.
Measure the actual values of these resistors.
Measure the actual power supply voltage.
Measure the voltage V1,V2 and V3.
Record these values in tables below.
Resistor
R Values
R1
50
R2
70
R3
100
I = 0.042 A
V=R*I
Voltage
Measured Voltage
Calculated Voltage
Error in %
V1
2.2V
50 x 0.042=2.1
1%
V2
2.9V
70 x 0.042=2.9
0%
V3
4.2V
100 x 0.042=4.2
0%
Vp
V1+V2+V3= 2.2+2.9+4.2=9.3
%Error=| Theoretical value – Experimental value / Theoretical value | x %
Part II: Kirchhoff’s Current Law
Build the circuit using Vp=10 v, R1=50, R2=70 and R3=100
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.
Resistor
R value
R1
50
R2
70
R3
100
Resistor
Voltage
Calculated Value
R1
10
10
R2
10
10
R3
10
10
I total= 0.43 A,
𝐼 = 𝑉/𝑅
%Error=| Theoretical value – Experimental value / Theoretical value | x %
Current
Measured Current
Calculated Current
Error in %
I1
0.19
10/50=0.2
0%
I2
0.14
10/70=0.14
0%
I3
0.1
10/100=0.1
0%
𝐼 𝑡𝑜𝑡𝑎𝑙 = 𝐼1 + 𝐼2 + 𝐼3 = 0.19 + 0.14 + 0.1 = 0.43 𝐴