laB rEpOrT kIRcHoFF'S rUlEs.docx

EXPERIMENT 5:KIRCHHOF’s RULES

ABSTRACT

The aim of this experiment to demonstrate kirchhoff’s Rules for electrical circuits .It used any of the resistors but except the 10 ohm one.Each observation, observation, find the value of resistance,voltage and currents for series and parallel circuit.From the experiment,the sum of the currents that f low into a junction,any electric connection must be equal the sum of the currents that flow out of the same junction,it is followed the condition of kirchoff’s Rules. Rules .

INTRODUCTION

In 1845, a German physicist, Gustav Kirchoff developed a pair or set of rules or laws which deal with the conservation of current and energy within electrical circuits, one of these laws deals with current flow, Kirchoff's Current Law, (KCL) and the other one which deals with with voltage, Kirchoff's Voltage Law, (KVL). Kirchoff's Current Law or KCL, states that the "total current or charge entering a  junction or node node is exactly equal equal to the charge leaving leaving the node node as it has no other other place to go except to leave, as no charge is lost within the node. Kirchoff's Voltage Law or KVL, states that "in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop" which is also equal to zero

OBJECTIVE

To begin the experimenting experimenting with the variables that contributes to the operation of an electrical circuit and to prove Kirchhoff’s Rules .

THEORY

Kirchhoff’s loop rules is an expression of energy conservation applied to changes in potential in a circuit.The electric potential must have a unique value at any point,the potential at a point cannot depend on the path one takes to arrive at that point.Therefore,if a closed path is followed in a circuit,beginning and ending at the same point.The algebraic sum of the potential changes must be zero

The sum of the currents entering a node must equal the sum of t he currents exiting a node.The first law is a simple statement of the meaning of potential. Since every point on a circuit has a unique value of the potential, travelling around the circuit, through any path must bring you back to the potential. Using the analogy to elevation: If one hikes from a starting point of a mountain, taking several paths, then finishes at the same point, the sum of the elevation changes of each path had better add to zero. The second law is the t he statment of current conservation mentioned before in the Ohm's law lecture. For the node on the right, i1=i2+i3. If all currents had been defined as enterning the node, then the sum of the currents would be zero.

APPARATUS 

Circuits Experiment Board



Wire Leads

 

Resistors



Two D-cell Batteries



Digital Multimeter (DMM)

METHODOLOGY/EXPERIMENTAL METHODOLOGY/EXPERI MENTAL PROCEDURE

1) The circuit was connected connected as shown shown in figure 2.1.The 2.1.The resistors used except except the 10Ω one. 2) The resistance values values was recorded recorded in the table.The table.The total resistance resistance of the circuit was measured with no current flowed. 3) The voltage across across each of the resistors was measured when the circuit connected to the battery and the current flowed.The values was recorded. 4) The current through through each each of the resistors resistors was measured.The circuit circuit was interrupted and placed the DMM in series. 5) The individually individually currents recorded,the recorded,the current current flowed into or out out of the main part of of the circuit,IT. 6) The circuit was connected connected as shown shown in figure 2.2.Step 2.2.Step 1 and step 5 was was repeated.

C

R2 R1

B A

R4 R3 D

FIGURE 7.1

R2

R4 R3 R1 V  2

V  1

R5

FIGURE 2.2

RESULT AND DISCUSSION

Resistance,Ω R1 330.5 R2 322.4 R3 325.6 R4 319.3 R5 99.5 RT 0.510k

Voltage,volts Voltage,volts V1 1.979 V2 1.927 V3 1.963 V4 1.924 V5 3.000 VT 3.890 TABLE 2.1

Current,mA I1 00.10 I2 00.10 I3 00.10 I4 00.10 I5 -00.01 IT 00.24

Resistance,Ω R1 330.5 R2 322.4 R3 325.6 R4 319.3 R5 99.5 RT 0.510k

Voltage,volts Voltage,volts V1 1.010 V2 0.984 V3 0.483 V4 1.446 V5 0.446 VT 3.433

Current,mA I1 0.060 I2 0.070 I3 -0.010 I4 0.110 I5 0.110 IT 0.110

TABLE 2.2 DISCUSSION

The sum of all currents entering a branch point of a circuit (where three or more wires merge) must be equal to the sum of the currents leaving the branch point

SAMPLE OF CALCULA C ALCULATION TION

∑Iin − ∑Iout = 0 RESULT 2.1 (I1+I3) – (I  – (I2+I4) = 0 (0.1+0.1) – (0.1+0.1) – (0.1+0.1)  (0.1+0.1) = 0 RESULT 2.2  – I5 (I1+I2) – I

 0



(0.06+0.07) – (0.06+0.07) – 0.11  0.11 =-0.02

CONCLUSION

From the experiment, we can conclude that the current enter and current leaving leaving same and summation both of it equal to zero. It also prove the kirchhoff’s rules that is ∑Ienter  - ∑Ileaving = 0.

RECOMMENDATION

1)

Make sure sure to choose the correct correct resistor for each each set of the experiment.

2) When using using the DMM, DMM, record the reading reading accurately. accurately. 3) Used wound and film resistors to get more precise reading. 4) Observe the unit showed in the DMM and make sure used the same unit for all calculations. 5) Connect the resistor resistor based on what what is shown in in the manual laboratory laboratory report report and make sure that the resistor is not touching each other.

REFERENCE

Multi-loop Circuits and Kirchoff's Rules.(2010).Retrieved Rules .(2010).Retrieved March 4, 2011 from http://physics.bu.edu/~duffy/py106/Kirchoff.html kirchhoff’s Rules,(2010),Retrieved Rules,(2010),Retrieved March 4,2011 4,2011 from

http://electron9.phys.utk.edu/phy http://electron9.ph ys.utk.edu/phys136d/modul s136d/modules/m6/kirchhoff.htm es/m6/kirchhoff.htm

Engineering Physics (CHE175) Laboratory Manual