Name:_______________________________    Course:____________  Date/Time:____________

Partner(s):_____________________________________________________________________

Purpose: 

Apparatus: Three resistors, 3 capacitors, circuit board, digital multimeter, and 2-banana plug wires w/alligator clip on one end.   

A. Resistors:

1. Determine the values of the three resistors using the resistor color code.                                                

2. Measure the values of the three resistors using the digital multimeter (DMM).

3. When two or more resistances are connected in series the equivalent resistance, R is give by;

When two or more resistances are connected in parallel the equivalent resistance, R is give by;

Connect the three resistors as shown below and measure the equivalent resistance.

Resistor combination	Resistance values
	Measured	Calculated
All in series
All in parallel

B. Capacitors:

When two or more capacitors are connected in series the equivalent capacitance, C is give by;

When two or more capacitors are connected in parallel the equivalent capacitance, C is give by;

                    Measured values: C₁= _______       C₂=_______    C₃=_{_______}

Capacitor combination	Capacitance values
	Measured	Calculated
All in series
All in parallel

C. Resistivity:

Purpose: To investigate the resistance of metal wires using a digital multi meter.

Apparatus: DMM, metal wire: one long and two short, connector box, micrometer, and meter stick.

Theory: Resistance, R of a metal wire of length l and cross-sectional area A is given by:

Procedure:

1. Set the DMM to measure resistances and connect two banana-plug wires from it to the connector box. 

2. Connect one end of the long metal wire to one of the terminals of the connector box.

3. Measure 10 cm length of wire, (do not cut the wire) and connect it to the other terminal so that there is exactly 10 cm of wire between the terminals.

4. Record the resistance value and repeat 3 for other lengths.

5. Plot a graph R versus length, and determine its slope.

6. Measure the diameter of the wire with a micrometer and calculate the resistivity of the metal.

DATA

Slope of R versus l, graph:_________________

Diameter of wire = __________________    Cross-Sectional area of wire =________________

Resistivity of wire = _________________

Now that you have seen what happens to the resistance as the length increases, can you predict what will happen to the resistance as the diameter increases?

PREDICTION:_________________________________________________________________

______________________________________________________________________________

You can check your prediction for the effect of diameter, by doing the following investigation, for a thin and thick wire of equal length:

Measure the resistance of the thin wire. Then measure the resistance of the thick wire.

EXPLAIN YOUR RESULTS:______________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Question: Electricity is transported across states using power lines with thick wires. Explain why?

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Include the following in your conclusion:

a. How does the length of wire affect the resistance of the wire and why?

b. How does the diameter of wire affect the resistance of the wire and why?

c. What information of the metal wire is provided by the slope of the R Vs. l, graph?