BME 153 Lab 1
Lab 1  Introduction to Laboratory Measurements
Nigel Chou Shijie
Lab Partner: Tim Liu
Section 1
September 12, 2007
I have adhered to the Duke Community Standard in completing this assignment.
_____________________________
Objectives
The objective of this lab is learn to measure current using a digital multimeter, and to demonstrate
Ohm’s law, first by showing how the current calculated by Ohm’s law correspond to values of current
measured directly, then by exploring the
i

v
relationships of various resistors. We also learned how to
measure power indirectly using voltage and resistance measurements, and to construct a voltage divider
circuit and understand how it works.
Apparatus
•
BK Precision 1652 Triple Output DC Power Supply
•
Fluke 45 Dual Display Bench Multimeter / Digital Multimeter (DMM)
•
Potentiometer
•
Various Resistors
•
Solderless breadboard
Procedure
1.
Current
: The circuit shown in figure 1 was assembled, with the power supply set to 5V
and the negative side connected to the frame ground of the power supply. The current through each
resistor was first determined by measuring the voltages across them and using ohm’s law, then
measured directly. The DMM was used for both voltage and current measurements.
2.
Ohm’s law
: The current through 3 resistors (560
Ω
, 1000
Ω
, 2200
Ω
) is measured as the
source voltage is varied from 1 to 10V. The Voltage is then plotted against current for each resistor.
3.
Power
: Using the circuit in Figure 2, 7 to 10 measurements of V
out
are taken over varying
resistances of the potentiometer, then the Voltages and resistances measured are used to calculate
power, which is plotted against the resistance of the potentiometer. Separate tests are done for a
source voltages of 8V,10V and 12V.
4.
Voltage divider
: The circuit in Figure 3 was set up, with R
1
and R
2
set as close as possible
to the values calculated in the Prelab (for R
2
, two resistors, one 2000
Ω
and another 510
Ω
were used
in series to simulate the 2533.3
Ω
resistor). 10 measurements of V
out
were made for various resistance
values (R
3
) of the potentiometer, then V
out
was plotted against R.
Data and Calculations
The uncertainty for handheld VOM is always half the smallest division.
The uncertainty for the
DMM when measuring resistance is 0.05% of reading + 2 digits where digits refers to the least significant
digit of the reading. Uncertainty for the DMM when measuring voltage is always 0.25% of reading + 6
digits.
1
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BME 153 Lab 1
NOTE
: In this lab, we unfortunately only took values to 3 significant figures instead of taking the full
reading. Thus the uncertainties will be measured based on these readings.
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 Fall '07
 MALKIN
 Voltage divider, Resistor, power supply, Electrical resistance

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