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)

                                      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.      How much current would you have gotten if you could have raised your voltage to 12 V? Explain your answer using and equation.

      (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 Readings (3 points each)

B. Voltage Readings

____ 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!!!!

 (4 points each)

C. Finding total resistance using 2 methods

 Method #1 - Use V_T  = I_TR_T  to find R_T (4 points) (Show all work) 

 Method #2 - Use R_T = R₁ + R₂ to find R_T      _______ ohms (4 points) (Show all work)

1) If you added another resistor to this circuit, what effect would it have on the size of the total current?  (3 points)  

   a) Use a relevant equation to explain why 6 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)