EXPERIMENT 5:KIRCHHOF’s RULES EXPERIMENT 5:KIRCHHOF’s RULES ABSTRACT
ABSTRACT
The aim of
The aim of this experiment to demonstrate kirchhoff’s Rules for electrical circuitsthis experiment to demonstrate kirchhoff’s Rules for electrical circuits .It.It used any of the resistors but except the 10 ohm
used any of the resistors but except the 10 ohm one.Each observaone.Each observation, find the valuetion, find the value of resistance,voltage and currents for series and parallel circuit.From the
of resistance,voltage and currents for series and parallel circuit.From the experiment,the sum of the currents that f
experiment,the sum of the currents that f low into a junction,any electric connectionlow into a junction,any electric connection must be equal the sum of the currents that flow out of the same junction,it is followed must be equal the sum of the currents that flow out of the same junction,it is followed the condition of
the condition of kirchoff’s Ruleskirchoff’s Rules..
INTRODUCTION INTRODUCTION
In 1845, a German physicist, Gustav Kirchoff developed a pair or set of rules In 1845, a German physicist, Gustav Kirchoff developed a pair or set of rules or
or laws which laws which deal with deal with the conservation of current and the conservation of current and energy within electricalenergy within electrical circuits, one of these
circuits, one of these laws deals with current flow, Kirchoff's laws deals with current flow, Kirchoff's Current Law, (KCL)Current Law, (KCL) and
and the other one the other one which deals wwhich deals with voltage, Kirchoff's Voltage Law, (KVL).ith voltage, Kirchoff's Voltage Law, (KVL). Kirchoff's Current Law or KCL, states that the "total current or charge entering a Kirchoff's Current Law or KCL, states that the "total current or charge entering a junction or no
junction or node is exactly equde is exactly equal to the charge lal to the charge leaving the nodeaving the node as it has no othee as it has no otherr place to go except to leave, as no charge is lost within the
place to go except to leave, as no charge is lost within the node.node.
Kirchoff's Voltage Law or KVL, states that "in any closed loop network, the total 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 voltage around the loop is equal to the sum of all the voltage drops within the same loop" which is also equal to zero
loop" which is also equal to zero
OBJECTIVE OBJECTIVE
To begin the
To begin the experimenexperimenting with the variables that ting with the variables that contributes to thecontributes to the operation of an electrical circuit and
THEORY THEORY
Kirchhoff’s loop rules is an expression of energy conservation applied to changes in Kirchhoff’s loop rules is an expression of energy conservation applied to changes in potential in a circuit.The electric potential must have a
potential in a circuit.The electric potential must have a unique value at any point,theunique value at any point,the potential at a point cannot depend on the path one takes to arrive at that
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 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
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
The sum of the currents entering a node must equal the sum of t he currents exiting ahe currents exiting a node.The first law is a
node.The first law is a simple statement of the meaning of potential. Since every pointsimple statement of the meaning of potential. Since every point on a circuit has a unique value of the potential, travelling around the circuit, through 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 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 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. same point, the sum of the elevation changes of each path had better add to zero. The second law is t
The second law is the statment of current conservation mentioned before in thehe 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 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.
as enterning the node, then the sum of the currents would be zero.
APPARATUS APPARATUS
Circuits Circuits Experiment Experiment BoardBoard
Wire Wire LeadsLeads
Resistors Resistors
Two Two D-cell D-cell BatteriesBatteries
METHODOLOGY/EXPERI
METHODOLOGY/EXPERIMENTAL MENTAL PROCEDUREPROCEDURE
1)
1) The circuit was coThe circuit was connected as shownnected as shown in figure 2.1.n in figure 2.1.The resistors used eThe resistors used except thexcept the 10Ω one.
10Ω one. 2)
2) The resistance vaThe resistance values was recolues was recorded in the tablerded in the table.The total resistan.The total resistance of the circuitce of the circuit was measured with no current flowed.
was measured with no current flowed. 3)
3) The voltage aThe voltage across each cross each of the of the resistors was measured resistors was measured when the when the circuitcircuit connected to the battery and
connected to the battery and the current flowed.The values was recorded.the current flowed.The values was recorded. 4)
4) The current thThe current through eacrough each of the resih of the resistors was stors was measured.The cimeasured.The circuit wasrcuit was interrupted and placed the DMM in series.
interrupted and placed the DMM in series. 5)
5) The indiviThe individually currents recodually currents recorded,the currenrded,the current flowed into or out flowed into or out of the main part ot of the main part off the circuit,I
the circuit,IT.T.
6)
6) The circuit was coThe circuit was connected as shownnected as shown in figure 2.2.n in figure 2.2.Step 1 and step 5 wStep 1 and step 5 was repeated.as repeated.
C C R R22 R R11 B B A A R R44 R R33 D D FIGURE 7.1 FIGURE 7.1
R R22 R R44 R R33 R R11 V V 22 V V 11 R R55 FIGURE 2.2 FIGURE 2.2
RESULT AND DISCUSSION RESULT AND DISCUSSION
Resistance,Ω
Resistance,Ω Voltage,volVoltage,volts ts Current,mACurrent,mA R1 R1 330.5 330.5 V1 V1 1.979 1.979 I1 I1 00.1000.10 R2 R2 322.4 322.4 V2 V2 1.927 1.927 I2 I2 00.1000.10 R3 R3 325.6 325.6 V3 V3 1.963 1.963 I3 I3 00.1000.10 R4 R4 319.3 319.3 V4 V4 1.924 1.924 I4 I4 00.1000.10 R5 R5 99.5 99.5 V5 V5 3.000 3.000 I5 I5 -00.01-00.01 RT RT 0.510k 0.510k VT VT 3.890 3.890 IT IT 00.2400.24 TABLE 2.1 TABLE 2.1
Resistance,Ω
Resistance,Ω Voltage,volVoltage,volts ts Current,mACurrent,mA R1 R1 330.5 330.5 V1 V1 1.010 1.010 I1 I1 0.0600.060 R2 R2 322.4 322.4 V2 V2 0.984 0.984 I2 I2 0.0700.070 R3 R3 325.6 325.6 V3 V3 0.483 0.483 I3 I3 -0.010-0.010 R4 R4 319.3 319.3 V4 V4 1.446 1.446 I4 I4 0.1100.110 R5 R5 99.5 99.5 V5 V5 0.446 0.446 I5 I5 0.1100.110 RT RT 0.510k 0.510k VT VT 3.433 3.433 IT IT 0.1100.110 TABLE 2.2 TABLE 2.2 DISCUSSION DISCUSSION
The sum of all currents entering a branch point of a circuit (where three or more 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 wires merge) must be equal to the sum of the currents leaving the branch point
SAMPLE OF C
SAMPLE OF CALCULAALCULATIONTION
∑Iin −
∑Iin − ∑Iout ∑Iout = 0= 0 RESULT 2.1 RESULT 2.1 (I (I11+I+I33)) – – (I (I22+I+I44) = 0) = 0 (0.1+0.1) (0.1+0.1) – – (0.1+0.1) = 0 (0.1+0.1) = 0 RESULT 2.2 RESULT 2.2 (I (I11+I+I22)) – – I I55 0 0 (0.06+0.07) (0.06+0.07) – – 0.11 =-0.02 0.11 =-0.02 CONCLUSION CONCLUSION
From the experiment, we can
From the experiment, we can conclude that the current enter and current conclude that the current enter and current leavileavingng same and summation both of it equal to zero.
same and summation both of it equal to zero. It also prove the kirchhoff’s rules that isIt also prove the kirchhoff’s rules that is ∑I
RECOMMENDATION RECOMMENDATION
1)
1) Make suMake sure to re to choose choose the correthe correct resistor ct resistor for eacfor each set h set of the of the experiment.experiment. 2)
2) When usinWhen using the Dg the DMM, record MM, record the readinthe reading accurateg accurately.ly. 3)
3) Used Used wound wound and and film film resistors to resistors to get get more more precise precise reading.reading. 4)
4) Observe the unit showed in Observe the unit showed in the DMM the DMM and make sure used and make sure used the same unit the same unit for allfor all calculations.
calculations. 5)
5) Connect the resiConnect the resistor based on wstor based on what is shown ihat is shown in the manual labn the manual laboratory repooratory report andrt and make sure that the resistor is not touching each other.
make sure that the resistor is not touching each other.
REFERENCE REFERENCE
Multi-loop Circuits and Kirchoff's Rules
Multi-loop Circuits and Kirchoff's Rules.(2010).Retrieved March 4, 2011.(2010).Retrieved March 4, 2011 from
from http://physics.bu.edu/~duffy/py106/Kirchoff.htmlhttp://physics.bu.edu/~duffy/py106/Kirchoff.html
kirchhoff’s
kirchhoff’s Rules,(2010Rules,(2010),Retrieved ),Retrieved March 4,201March 4,20111
from
fromhttp://electron9.phhttp://electron9.phys.utk.edu/phyys.utk.edu/phys136d/moduls136d/modules/m6/kirchhoff.htmes/m6/kirchhoff.htm
Engineering Physics (CHE175) Laboratory Manual Engineering Physics (CHE175) Laboratory Manual