Lab 8 - lab report PDF

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QUEENSBOROUGH COMMUNITY COLLEGE The City University of New York

Department of Engineering Technology

ET 110 – Electric Circuit Analysis Laboratory

Lab # 8 –Series-Parallel Circuits and In-circuit Resistance Measurement

Student’s Name: Umer Ali

Fall 2015 Submitted Date: 11/24/15 Grade:

Prof.Huixin Wu

 Objectives:

1. 2. 3. 4. 5.

Wires Batteries Resistors Multi-Meter Bread Board

 Experimental: Table 8.1 Current through 100Ω Resistor 23.4mA

Measured

Current through 330 Ω Resistor 15.8mA

Current through 680 Ω Resistor 7.7mA

Does KCL Hold? Yes

Table 8.2

Measured

Voltage at Node A

Voltage at Node B

Voltage across 100Ω Resistor

Voltage across 330Ω Resistor

Voltage across 680 Ω Resistor

Is Voltage across R2 and R3 is Same?

Does KVL Hold?

7.4V

5.1V

2.3V

5.1V

5.1V

Yes

Yes

Table 8.3

Expected What Does the Ohmmeter Measure?

Resistance when Ohmmeter is Across 100Ω Resistor 100Ω 100Ω

Resistance when Ohmmeter is Across 330Ω Resistor 222Ω 222Ω

Table 8.4 IRI Expected

29.3 mA

IRI

IRI

IRI

VR1

VR1

VR1

VR1

VA

VB

VC

RT

Measured

23.8 mA

13.4m A

13.3m A

10.4m A

2.2 V

1.9 V

2.9 V

4.9 V

7.3 V

4.9 V

2.9 V

3.6 Ω

 Answers to Questions: 1. We can do it by using the ‘RT’ formula or by ‘Ohms’ law, if we have the voltage and current measurements. 2. First we add up all the resistors connecting in parallel and measure the total resistance. Then we consider those resistances as a one resistance and measure it with other resistors connected in series. 3. When an ohmmeter is placed across a resistor, it measures the resistance of the resistor or its voltage, depends on what we want to measure. If we take out one leg of resistor then it measures the current.

 Conclusion: In this lab, we learned about series-parallel circuit like how to measure the current, voltage and resistance across a series-parallel circuit. In this lab, we use the bread board, resistors, battery, wires and digital multi-meter (DMM). It was a kind of fun though to connect these things together and measure voltages and currents. First we build up a circuit on bread board with the help of resistors, wires and battery (9V). We measured the current across each resistor and see that is the circuit hold KCL or not. Besides this we measure the voltage across each resistor by putting the multi meter into voltage mode, we also see that voltage across R2 and R3 is same. Further this also holds the Kirchhoff’s Voltage Law (KVL) or not. Then we measure the resistance across each resistor by taking out the voltage source from the circuit. After that we made one more series parallel circuit. This time we use 4 resistors with one battery source and build up a series parallel circuit. We start measurements by measuring the current across each resistor then voltage and at the end we measure the total resistance....