Lab Report for CSE 109East West University

Lab Experiment Number: 01Experiment Title: Introduction to Circuit Elements and Variables

Prepared By:Kazi Hasibul Kabir2014-1-60-042Date of Experiment: 25.09.2014Date of Report: 23.10.2014Course Code: CSE 109Instructor Name: Fahmida Azmi

Group InformationGroup Number: 03Md. Nazmul Hasan (2014-1-60-041)Kazi Hasibul Kabir (2014-1-60-042)Md. Zahiruddin Aqib (2014-1-60-047)

Introduction:There are two types of elements in an electric circuit active elements and passive elements. An active element supplies energy. A voltage source or a battery is an active element. The emf of a battery is measured using the unit volt (V). A passive element absorbs energy. A resistor is a passive element. The resistance of a resistor is measured using the unit Ohm ().There are two fundamental circuit variables current through circuit element and voltage across as circuit element. The through a circuit element is measured using the Ampere (A) and voltage across a circuit element is measured using the unit Volt (V).A simple electric circuit is shown in figure. The emf of the battery is E Volt and the resistance of the resistor is R . The current drawn from the battery and the current passing through the resistor are same and is I A. The voltage drop across the resistor is exactly equal to the emf of the battery, that is E.The ohms law relates that V=IR. If we plot V vs. I (taking I as independent variable), we have a straight line passing through the origin and the slop of the line is R.

Figure: A simple electric circuit.An ammeter is used to measure current and a voltmeter is used to measure voltage. As an ammeter is connected in series with an element, current through which is to be measured. A voltmeter is connected in parallel with an element, voltage across which is to be measured. If you connect an ammeter in parallel with an element, the meter will be damaged. If you connect a voltmeter in series with an element, it will not give you correct result. So, make sure that an ammeter is not connected in parallel and a voltmeter is not connected in series.

Circuit Diagram:

Figure: Circuit for experiment.

Experimental Procedure:1. Measure the resistance of the resistor supplied using a multimeter and record in datasheet.2. Construct the circuit of Figure. Set the value of E at 5, 6, 7, 8, 9 and 10 volts and measure the corresponding V and I and record them in datasheet.3. Have the datasheet signed by instructor.

Answer to the Post-Lab Question:1. Calculations:We know, From Ohms Law, Voltage V=IR. When E=5 V and R=1000 , When E=6 V and R=1000 , When E=7 V and R=1000 , When E=8 V and R=1000 , When E=9 V and R=1000 , When E=10 V and R=1000 , Observation numberSet value of E (V)Measured Value of V (V)Measured Value of I (mA)Measured of R ()

1555.1

969

2666.1

3777.1

4888.1

5999.1

6101010.1

Comments:By comparing both the measured and theoretical values it is seen that there are some variations in the values but the readings were taken according to the instruments. So, there are some errors in the instruments.

2. Calculations:We know, From Ohms Law, Voltage V=IR. When I=5mA and E=5 V, =1000 When I=6mA and E=6 V, =1000 When I=7mA and E=7 V, =1000 When I=8mA and E=8 V, =1000 When I=9mA and E=9 V, =1000 When I=10mA and E=10 V, =1000

Observation numberSet value of E (V)Measured Value of V (V)Measured Value of I (mA)Measured of R ()

1555.1

969

2666.1

3777.1

4888.1

5999.1

6101010.1

Comments:By comparing both the measured values and calculated values of the resister are not same. So, some errors were made during doing the experiment and taking the reading of the measured values. These were caused by errors and instruments. But the readings were taken according to the instrument.3. The comparison between the set value of E and measured value of V are given below:Measured values of V(V)Set values of E(V)

55

66

77

88

99

1010

Comments:By comparing both the values it is seen that the set value in the dc power supply are same.

4. The graph of V vs. I is shown below :

In the graph, when V= 5 V and I= 5.1mA, =980.39 When V= 6 V and I= 6.1mA, =983.61 When V= 7 V and I= 7.1mA, =985.92 When V= 8 V and I= 8.1mA, =987.65 When V= 9 V and I= 9.1mA, =989.01 When V= 10 V and I= 10.1mA, =990.11The value from graph and the measured values are compared in the table below:Measured value of R(Ohm)Value of R from Graph

1000980.39

1000983.61

1000985.92

1000987.65

1000989.01

1000990.11

Comments: From the above table it is seen that in all cases the measured values of resistance is 1000 . But for every volts, there is a little variation between the measured value of R and the value of R taken from the graph. 5. In the circuit, while doing the experiment, voltage of two points is measured very carefully by connecting the voltmeter in parallel connection across the point. Current passing through the circuit is measured in series by using a multi-range meter.

Result:After comparing the theoretical & measured values of I, V, R, we found that there some change with the values. This change is occurred by instruments.

Conclusion:While doing the experiment, utmost care was taken in order to take the readings very carefully. The circuit was connected very carefully to prevent short circuit. Lastly by doing the experiment, we have gained practical knowledge about how to work with circuits.