Circuits                                  Name:_______________________________________

Partner(s):______________________Date:______Time:_______Course:___________

A. Ohm's Law

Purpose: To investigate Ohm’s law and measure resistances.

Apparatus: DC power supply, rheostat (89 ohm), 6- connecting wires (banana plug), 2-alligator clips, 5-ohm resistor, 10-ohm resistor, light bulb (6.3A,0.5A), and 2- digital multi meters (DMM).

Theory

Procedure:

1. Call the instructor to check the circuit. 

2. Set the current, measure the voltage, and then calculate R.

DATA:     Unknown resistance: 5-ohm resistor.

Current, I (A)

Voltage, V(   )

Resistance, R(   )

0

0

XXXXXXXXX

0.05

-

-

0.10

-

-

0.15

-

-

0.20

-

-

0.25

-

-

0.30

-

-

0.35

-

-

0.40

-

-

3. Turn the dial in the power supply to zero current & voltage.

4. Look at the resistance values and predict the V versus I relationship for the 5-ohm resistor.

____________________________________________________________________

5. Plot V versus I, and determine the slope.  Slope = _________________________


DATA:     Unknown resistance: 10-ohm resistor.
6. Set the current, measure the voltage, and then calculate R.

Current, I (A)

Voltage, V(   )

Resistance, R(   )

0

0

XXXXXXXXX

0.05

-

-

0.10

-

-

0.15

-

-

0.20

-

-

0.25

-

-

0.30

-

-

0.35

-

-

0.40

-

-

7. Turn the dial in the power supply to zero current & voltage.

8. Look at the resistance values and predict the V versus I relationship for the 10-ohm resistor.

____________________________________________________________________

9. Add this plot of V versus I, to the earlier graph and determine the slope.  

Slope = __________________

10. Print a hard-copy of your graphs.

DATA: Unknown resistance, LIGHT BULB.

11. Set the current, measure the voltage, and then calculate R & P. (Include units for V, R, and P)

Current, I (A)

Voltage, V(__)

Resistance, R(__)

Power, P(__)

0

0

XXXXXXXXXX

-

0.01

-

-

-

0.025

-

-

-

0.05

-

-

-

0.075

-

-

-

0.10

-

-

-

0.15

-

-

-

0.20

-

-

-

0.25

-

-

-

0.30

-

-

-

0.35

-

-

-

12. Look at the resistance values and predict the V versus I relationship for the light bulb. 

____________________________________________________________________

13. Plot V versus I, on a separate graph and print a hard-copy.

14. Attach your graphs, write a conclusion, and attach it too.

 

 

B. Circuits with Resistors and Capacitors 

Purpose: To investigate various combinations of resistors and capacitors. 

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) as shown below.

3. Observe the tolerance values and record them in the data table. 

 

R1

R2

R3

From resistor color code

 

 

 

From digital multi- meter

 

 

 

Tolerance

 

 

 

When two or more resistances are connected in series the equivalent resistance, RS is given by;                        

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

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

5. Also calculate the equivalent resistance values using the DMM values for individual resistances.

Data:

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, CS is given by;

         

      

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

                   

6. Measure the values of the three capacitors using the digital multimeter (DMM) as shown here.  

7. Connect the three capacitors as shown below and measure the equivalent capacitance.

8. Also calculate the equivalent capacitance values.


DATA: Capacitors

Measured values: C1= _______       C2 = _______    C3 =__________

Capacitor combination

Capacitance values

Measured

Calculated

All in series

 

 

 

All in parallel