Name
_________________________
# ______ Date
___________
Name
_________________________
# ______ Section #__________
Name
_________________________ # ______
Series
Circuit Lab
Assign a group member to
one of the following roles:
· Recorder (Records data) __________________________________________
·
Reader (Reads instructions and checks off each procedure
upon completion)
______________________________________________________________
· Circuit Constructor and Meter Reader _________________________________
I. Constructing Series Circuit #1 – One Unknown
Resistor
Check off
each procedure upon completion
___ Construct the series circuit pictured below.
Reverse terminal connections if meter needle moves backward
Calculating the value of the unknown resistor –
Do you
have the F or TS resistor?
____ Plug in the voltage source and
turn on the power.
____ Turn the dial on the voltage source until you reach the maximum voltage
____ Read the current and voltage
and record it in the data table
____ Calculate the resistance using the
Ohm’s Law equation. Record the resistance.
____ Record voltage measurements of 3
other current readings (include
a wide range of numbers)
____ Unplug your voltage
source
***** Important!! Reading the scales: *****
Voltmeter - Read middle scale Ammeter - Read
lower scale
Small divisions on Voltmeter =
________Small divisions on Ammeter = _______
Ohm’s Law: Voltage = Current X Resistance (V = I R)
(3 points
each)
|
Voltage (volts) |
Current (Amperes) |
Calculation of Unknown Resistance (Ohms) |
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Average
Resistance Value: ________ ohms (2 points)
Follow-up
Questions
1.
According
to Ohm’s Law, what is the mathematical relationship between voltage and
current? (4 points)
Direct? Direct
Square? Inverse? Inverse Square?
2.
Explain
why you think your voltage and current readings support or reject the
mathematical relationship you gave in the question above. Refer to your
numbers in your explanation.
(4 points)
3.
If
you plotted your Voltage versus Current data what do you predict the general shape of
your plot would be? (4 points)
II.
Constructing Series Circuit #2 – 2 Resistors in connected in series
What is the
size of the resistance of your second resistor? _______________ ohms
____
Return your voltage source to the side of the room (You’ll be using the source
on lab desk)
____Open
up your circuit and add your other resistor to your circuit.
30 ohms
resistor
Voltage and Current Readings
____ Look up the series circuit
equations in your reference table. Write them below. (4 points)
____ Plug in the voltage source that is built into your lab
desk.
____ Use your ammeter to fill out the
table below
Current
|
Total
Current from Ammeter (IT) (amps) |
Current
in Unknown
Resistor (I1) (amps) |
Current
in
30
ohm resistor (I2) (amps) |
|
|
|
|
B. Voltage
____ Measure the voltages in both
resistors. Find the total voltage using the appropriate series circuit
equation. DON’T MEASURE THE
TOTAL VOLTAGE WITH METER – USE A SERIES CIRCUIT EQUATION!!!!
|
Measured Voltage in
Unknown Resistor (V 1) |
Measured Voltage in 30
ohm Resistor (V2) |
Total Voltage from
Source (VT ) (Calculated from Equation on your reference table) |
|
_____________ volts |
_____________ volts |
_____________ volts |
C. Finding total
resistance using 2 methods
|
Total Voltage from
Source (VT) (See Table Above) |
Total Current from
Source (I T) (See previous page) |
Total Resistance (RT) (Calculate) (4 points) |
|
______________volts |
_______________ amps |
____________ ohms |
1) If you added another
resistor to this circuit, what effect would it have on the size of the total
current?
(3 points)
2) If the total voltage supplied to your circuit remained unchanged, how much resistance must be added to your circuit to achieve a total current of .1 amperes? (Show all work) (6 points)