Download a. Construct a simple circuit similar to the light bulb circuit in the

Electric Circuits
(Turn in an answer sheet with all drawings, measurements and answers
labeled to correspond to the following.)
This lab will demonstrate Ohm’s Law and some of the characteristics of
series circuits and parallel circuits. In addition, it will emphasize the
contrasting characteristics of the two types of circuits.
I. Pathways for current
a. Construct a series circuit, using jumper wires, a power supply set to
minimum DC output, and 2 bulb sockets with bulbs. Draw a picture
of your circuit. __________
b. Adjust the power supply to produce an orange glow in all 2 bulbs.
Unscrew one of the bulbs. Replace the bulb and unscrew another.
What happens?________________
c. What do these observations tell you about the pathway for current in a
series circuit?_____________
d. With the same materials, construct a parallel circuit. (Again, use the
minimum DC output.) Draw a picture of your circuit. __________
e. Unscrew one of the bulbs. Replace the bulb and unscrew another.
What happens?_______________
f. What do these observations tell you about the pathway for current in a
parallel circuit?_______________
II. Voltage
a. Construct a functioning series circuit with 2 bulb sockets.
b. Use a multimeter to measure the voltage across both bulbs, by
touching one probe to the negative side of the 1st bulb and touching
the other probe to the positive side of the last bulb.
c. Record the total voltage _____________
d. Using a similar procedure, measure the voltage across each bulb
separately. _________, _________
e. Use a multimeter to measure the voltage across the jumper wire in
between the 2 bulbs. ______________
f. Why do you think we should make this measurement? _________
g. What do these observations tell you about voltage in a series
circuit?___________
h. Construct a functioning parallel circuit.
i. Use the multimeter to measure the voltage from one “junction”
leading into the parallel branches to the other “junction”. Record the
total voltage. _____________
j. Using a similar procedure, measure the voltage across each bulb
separately. __________, __________
k. What do these observations tell you about voltage in a parallel circuit?
____________________
III. Current
a. Construct a functioning series circuit with 2 bulb sockets.
b. Replace the wire from the negative side of the power supply with the
multimeter in ammeter mode, set on the highest scale, 20 A. Check
with your instructor before changing to a lower scale. Record the
current. _____________
c. Replace the original wire from the power supply. Then, replace the
jumper wire between the 1st and 2nd bulb with the ammeter. Record
the current._______________
d. What do these observations tell you about the current in series circuit?
______________
(Optional-as directed by your instructor)
e. Construct a functioning parallel circuit with 2 bulb sockets.
f. Replace the wire from the negative side of the power supply with the
multimeter set on 20 A. Check with your instructor before changing
to a lower scale. Record the current. ______________
g. Replace the original wire from the power supply. Then, replace one
of the wires leading from the junction into a bulb socket with the
ammeter, set at 20 A. Check with your instructor before changing to a
lower scale. Record the current. ___________
h. What do these observations tell you about current in a parallel circuit?
IV. Resistance (Optional-as directed by your instructor)
a. Use Ohm’s law and your answers from II d and III b to calculate the
resistance of the entire series circuit. _______________
b. Use Ohm’s law and your answers from II f and III c to calculate
(estimate) the resistance for each bulb separately. ________,
________
c. Taking into consideration the resistance of the jumper wires, what do
these observations tell you about resistance in a series circuit? ______
d. Use Ohm’s law and your answers from II i and III f to calculate the
resistance of the entire parallel circuit. ____________
e. Use Ohm’s law and your answers from II j and III g to calculate
(estimate) the resistance for each bulb separately. ______, ________
f. Taking into consideration the resistance of the jumper wires, what do
these observations tell you about resistance in a parallel circuit? _____
V. Ohm’s Law
a. Construct a simple circuit similar to the light bulb circuit in the
previous lab, but use a resistor instead of the light bulb. Use a
galvanometer to set the current through the resistor to as close to 200
A as possible, as you slowly turn the voltage knob from zero to a
positive value.
b. At this point, record the exact current _______________
c. Without changing the voltage setting, use the multimeter to measure
the voltage drop across the resistor ______________
d. Use Ohm’s Law to calculate the observed value of the resistance in the
resistor ____________
e. Use the multimeter as an ohmmeter to measure the accepted value of
the resistor __________
f. Also, use the color code, provided by your instructor, to determine the
accepted value of the resistor ______________
g. Determine the % discrepancy between the observed and accepted
values, using the formula, (O-A)/A * 100 ______________ (Ohm’s law)
(O-A)/A * 100 ______________ (multimeter)