Download Voltage, Current, and Resistance

EGN 100 Introduction to Engineering
Resistance, Voltage, and Current Laboratory Guidelines
The objectives of the laboratory are:
 Become familiar with the instrumentation
 Measure voltage and current
 Draw circuit diagrams
 Determine the relationship between voltage, resistance and current for a single resistance and
for multiple resistances in series
A. Relationship among voltage, resistance, and current
Construct a circuit as shown in the diagram and the photograph. Use a 10 ohm resistor. Set the
power supply voltage to 0 volts.
Ammeter
Power
Supply
R
Voltmeter
For the following supply voltages, measure and record:
Supply Voltage
Current through the 10 ohm resistor
Voltage across the 10 ohm resistor
Disconnect the circuit from the supply.
0.0
2.0
3.0
4.0
volts
amperes
volts
Repeat for the 5 ohm resistance.
Each person, using a spreadsheet, plot for the 10 ohm resistance the relationship between the
voltage across the resistance (on the vertical axis) and the current through the resistance (on the
horizontal axis). Since the plot is from a set of data, plot the points and find the best fit straight
line, including the best fit equation for the line but not R2. Since we know that there is zero
current for zero voltage, set the y intercept to zero when setting up the best fit straight line.
What is the equation describing the line?
What is the slope of the line?
Repeat for the 5 ohm resistance.
Compare the results for the 10 ohm and the 5 ohm resistances.
B. Resistance, current and voltage in a single loop with two resistors
Using the 10 ohm resistance and the 5 ohm resistance in series construct a circuit as shown in the
Ammeter
Supply
10 ohms
Voltmeter
5 ohms
diagram. Set the voltage to 4.0 volts. Connect the supply to the circuit. The diagram shows
voltage being measured across the 5 ohm resistor.
Measure and record:
Supply voltage
4.0
Current
Voltage across 5 ohm resistor
Voltage across 10 ohm resistor
Voltage across ammeter
volts
amperes
volts
volts
volts
What is the relationship between the voltage across each resistor and the current through that
resistor?
How does the sum of the voltages across the resistors and the ammeter relate to the supply
voltage? Calculate the resistance of the ammeter.
Using the data you obtained in class, answer the lab questions and describe whether and how the
lab results conform to the principles you have learned in this class session. Name the file
XVoltageCurrentResistance.doc, where X is your last name.
Upload the file to your folder named Laboratories.