Experiment 3 Ohm’s Law and ResistanceBy: Aisha Ali Sulaiman Mohamed Alnaqbi H00367954Partners: Alya Mohamed Ali Omani Alnaqbi H00351803 Ghayah Mohammed Karam Jalal Alkaabi H00368030 Class: 15356For: Mr. Wassel Al AbbasDate: 18/10/2018 INTRODUTION:- Objective: 1-This experiment will show the relationship between the voltage(V) , resistance(R) and current(I) in a circuit2-prove the Ohm’s Law.3-Find the total resistance for series and parallel connection circuit Theory: The relationships states that the voltage across a conductor between to point’s is directly proportional to the current.

The constant of proportionality is called “resistance”. Ohm’s law expression: V=I RWe have two types for connecting the resistance:- total resistor in a series circuitR = R1 + R2 + R3…..Rn total resistor in a parallel circuitR=(??R1?^(-1)+?R2?^(-1)+?R3?^(-1)+?Rn?^(-1)…)?^(-1)we have to connect the Ammeter in series to measure the currentwe have to connect the Voltmeter in series to measure the voltage Material and equipment: Varied values of resistors Power supply Power supply cables Connecting wires Multimeter Breadboard Jumper wires Experimental set up and Procedure: Measure using Multimeter the resistance of the three resistors listed in the table below Table.

1 . Use breadboard to connect R1 = 1.0 k into the circuit as shown in Fig. Adjust the power supply voltage at 2.

0 V. Measure and record the current in Table.2 below: – Vary the voltage value as per the table below and record corresponding current reading for each of the voltages listed in the table below. Draw I-V curve using the data from the above table Table.2.

Plot the current on the y-axis and the ?voltage in the x-axis. Find the slope of the straight line and compare with the value of R1 . ?Comment on the graph. ? Replace R1 with R2 & R3 connected in series and repeat steps 3. Record the data in Table.

3 ? Draw I-V curve using the data from the above table Table.3. Plot the current on the y-axis and the voltage in the x-axis. Find the slope of the straight line and compare it with the value of RT ( RT measured by Ohmmeter ) .

Comment on the graph. ? Connect R2& R3 in parallel and repeat steps 3. Record the data in Table.4 below: ? Draw I-V curve using the data from the above table Table.4. Plot the current on the y-axis and the voltage in the x-axis.

Find the slope of the straight line and compare it with the value of RT ( RT measured by Ohmmeter ) . Comment on the graph. Data: Table1 Resistors Listed value Ohmmeter Value Multisim Value R1 1.0k? 0.994 k? 1.

0k?R2 2.2k? 2.199 k? 2.2k?R3 3.3k? 3.360 k? 3.

3k?Table2Vs 2.0v 4.0v 6.0v 8.0v 10.0v 12.0vBreadboard I 2.

06mA 4.13mA 6.19mA 8.20mA 10.27mA 12.

41mAMultisim I 2mA 4mA 6mA 8mA 10mA 12mACalculation I 2mA 4mA 6mA 8mA 10mA 12mA Table3Vs 2.0v 4.0v 6.0v 8.0v 10.

0v 12.0vBreadboard I 0.37mA 0.72 mA 1.09 mA 1.46 mA 1.

82 mA 2.18 mAMultisim I 0.363mA 0.

727mA 1.091mA 1.455mA 1.

818mA 2.182mACalculation I 0.363mA 0.

727mA 1.091mA 1.455mA 1.818mA 2.182mATable4Vs 2.0v 4.0v 6.

0v 8.0v 10.0v 12.0vBreadboard I 1.55mA 3.

08 mA 4.62 mA 6.16 mA 7.65 mA 9.20 mAMultisim I 1.

515mA 3.03mA 4.545mA 6.06mA 7.575mA 9.09mACalculation I 1.515mA 3.

03mA 4.545mA 6.06mA 7.

575mA 9.09mA Sample calculated value:The result of calculate the current when the voltage is 2V and the R_1=1k?R_1=1k? V=2VI=V/R=2/1=2mAThe result of calculate the total resistance ?(R?_T) when R_2=2.2k? and R_3=3.3k? connected in series:R_2=2.2k? R_3=3.3 k? V=2VR_T= R_2+R_3 R_T=2.

2+3.3=5.5k?The result of calculate the current when the voltage is 4V and R_2=2.2k? and R_3=3.3k? connected in series: I=Vtotal/Rtotal=4V/(5.5K?)=0.727mAThe result of calculate the total resistance ?(R?_T) when R_2=2.2k? and R_3=3.

3k? connected in parallel:-R_2=2.2k? R_3=3.3 k? V=2VR_T=(??R_2?^(-1)+?R_3?^(-1))?^(-1)R_T=(??2.2?^(-1)+?3.3?^(-1))?^(-1) = 1.32k?The result of calculate the current when the voltage is 4V and R_2=2.2k? and R_3=3.

3k? connected in parallel: I=Vtotal/(R totl)=4V/(1.32K?)=3.03mAMultisim:Measure the resistance in the resistor:- Measure the Current on 1.0K? resistor:- Measure the Current on 2.2k? resistor and 3.3k? resistor connected in series Measure the Current on 2.2k? resistor and 3.3k? resistor connected in parallelAnalysis: There’s only less percentage of error in the solutions because when we find the voltage and the current in the multimeter we didn’t but the exact value .

Conclusionto sum up, Ohm’s law can used in both parallel and series circuits. In parallel circuits , there are more than one path each bath has same voltage while the current is different . on the other hand In series circuits , there is only one path which has same current and different voltage. ReferencesMultisimWikipediaCircuit lab manual Review questions: Three resistors are connected in parallel across 50V , the values of the resistors are 620? , 750 ? and 1200 ? : What is the value of the total current?I=V/R I=?V=50VRT = ? (?620?^(-1)+ ?750?^(-1)+?1200?^(-1))?^(-1) = 264.58 ?I=50V/264.58 ? I=188.98mA?b.

If one of the resistors were shorted, what would you expect to see happen? Short will cause a direct circuit path between the negative and positive terminal leads of the power supply. So the wire would get very hot and maybe melt open or burn the insulation. 2. What is the difference between the value of RT if the resistors are connected in series and value of RT if the resistors are connected in parallel.-RT when we connected the resistors in series is larger than the largest resistor -RT when we connected the resistors in series is less than the smallest resistor