Download Series Cicuit Lab

Ohm’s Law in Series Circuit Lab
Page 1 of 4
Objectives: The purpose of this lab exercise will be to reinforce concepts learned in the classroom
segment of Electricity/Electronics. These concepts include: series connected resistance is additive,
voltage drop is additive, and current measurements through-out the circuit is the same. . Students
will gain experience in building prototype circuits, making measurements and proving experimentally
fundamental electricity principles. Remember from the previous lab, students learned that current
must be measured in series with the load. In this lab, lamps have been replaced with a very basic
solid state component know as an LED.
Procedure:
A. Series connected resistance
1. Read the entire lab exercise before coming to class to complete the lab assignment.
2. Record the rated resistance on the schematic diagram and in the rated resistance row
of the chart.
3. Measure the resistance of each of the resistors individually and record the
measurements in the space provided in the chart.
4. Connect the resistors in series according to the schematic diagram, measure the total
resistance for the series connected resistances and record the measurement in the
Rmeas. row and the Rtotal column.
R1
R2
value
value
R1
Rrated
Rmeas.
Rcalc.
R3
R4
value
R2
R3
value
R4
Rtotal
Ohm’s Law in Series Circuit Lab
Page 2 of 4
Procedure:
B. Series voltage drops
1. Read the supplement containing the information regarding the LED. Keep in mind that
LED’s are polarity sensitive devices and must be connected correctly in order to be
operational.
2. Construct the circuit at the top of the next page using jumper wires between each of the
LED’s as indicated by the schematic diagram. There is a photograph to assist you with
the construction of the circuit. Set the voltage for the value outlined during the
classroom introduction for this lab exercise.
3. For each measurement observe the correct meter polarity.
4. Measure the voltages across the LED’s and record the measurements in the spaces
provided.
5. Measure the currents between the indicated points with the jumper wire removed and
record the current measurements in the space provided in the chart.
6. For ET below add all of the measurements from the first column and record this as E T.
(ET = EJ-I + EH-G + EF-E + ED-C)
7. Be sure to answer the questions at the end of this exercise as this is an excellent way to
check an individual’s understanding.
D1
K
J
D2
I
H
D3
G
F
D4
E
D
V1
A
B
0
EJ-I
EH-G
EF-E
ED-C
EA-K
IK-J
EA-K
II-H
switch open
EA-B
switch open
ET
IG-F
IE-D
IA-B
switch open
IA-B
switch closed
PT
C
Ohm’s Law in Series Circuit Lab
Page 3 of 4
Questions:
1. What has been proven about current in a series circuit?
2. Describe what happened to the circuit the instant one of the jumper wires was removed for
measuring current?
3. Did the LED’s produce much heat? Explain your answer.
4. List five common applications for LED’s
a.
b.
Ohm’s Law in Series Circuit Lab
Page 4 of 4
c.
d.
e.
5. Describe what you know about resistance in series.
6. How much voltage did one LED drop?
7. What were the color bands on R1?
8. What were the color bands on R3?
9. List some of the advantages of using LED’s over incandescent lamps.
a.
b.
c.
10. Describe how to identify the leads of a diode.