Become familiar with resistors and the resistor color code
Become familiar with power supplies, multimeters, and ammeters
Gain experience measuring resistance, voltage, and current
Preparation:
Determine and record in your lab book the color code for each of the following resistors:
56 Ω
820 Ω
3.9 kΩ
5.1 kΩ
12 kΩ
Determine and record in a table the possible range of resistance values for each of
the resistors above if the fourth color is gold and also if the fourth color is silver.
Equipment and Parts:
Power Supply
Digital Multimeter
Analog Ammeter
Resistors: 56 Ω, 820 Ω, 3.9 kΩ, 5.1 kΩ, & 12 kΩ
Procedure:
Record in your lab book the make and model of the digital multimeter, the power supply,
and the ammeter.
Obtain one each of the resistors from the preparation. Measure the resistance of each
of the resistors using the digital multimeter. Be sure not to touch the test leads
or resistors leads while making the measurements. Record the measured value, the percent
difference from the reported value and indicate whether each is within the reported
range (tolerance).
Measure the resistance of each of the first two resistors by holding the test leads
on the resistor leads with your hands. Record the measured value. Compare these results
with the results from step 2. If they are different, suggest why.
Measure the hand-to-hand resistance of all lab partners by gripping the test leads.
Record your results.
Connect the 3.9 kΩ and the 5.1 kΩ resistors in series. Measure and record the total
resistance of the combination.
Calculate the current that would flow through the combination if connected across
a 9 V power supply. Calculate the voltage across each resistor for the calculated
current flowing through the resistors.
Set the power supply output voltage to 9 V. Measure the supply voltage using the multimeter.
Record the measured voltage. Adjust the supply voltage to a measured 9 V.
Connect the power supply across the resistor combination. Measure and record the voltage
across each resistor. Calculate and record the actual current flowing through each
resistor. Measure the current flowing by inserting the ammeter in series with the
power supply and resistor combination. Record the measured current flowing through
the circuit.
Measure and record the voltage as a function of current for a 56 Ω resistor. Do this
by connecting the power supply, ammeter, and resistor in series. Start with the power
supply turned down to 0 V. Adjust the supply voltage up until 10 mA flows through
the circuit. Measure the voltage across the resistor using the multimeter. Continue
to adjust the supply voltage so that the current increases in increments of 10 mA
to maximum of 100 mA current or 10 V voltage and record the voltage across the resistor
for each increment.
Repeat step 9 for a wire filament lamp.
Repeat step 9 for a light emitting diode (LED).
Plot the voltage as a function of current for all three on one graph.
