PASCO

MAIN PROCEDURE
In this experiment, students determine the relationship between the voltage, current, and power of the primary and secondary coils of a transformer.
 
  1. Press in DataStudio.

  2. Adjust the switches on the Decade Resistor Box to produce 50 Ohms of resistance.

  3. Adjust the V/div arrows to maximize the wave form of the Primary Coil Voltage.

  4. Click on the Smart Tool .

  5. Place the cursor over the Smart Tool crosshair until it transforms into the Delta Tool cursor .

  6. Drag the Delta Tool cursor to the maximum amplitude of the Primary Coil Voltage.

  7. Enter the value of the maximum amplitude of the Primary Coil Voltage into the Data/Analysis Table.

  8. Repeat steps 3-7 for the Secondary Coil Voltage, the Primary Coil Current and the Secondary Coil Current.

  9. Repeat steps 2-8 for the remaining resistances.

  10. Press in DataStudio.
DATA ANALYSIS TABLE
  Primary Coil Secondary Coil
Resistance
(Ohms)		 Voltage
(V)		 Current
(I)		 Power
(W)		 Voltage
(V)		 Current
(I)		 Power
(W)
50            
100            
150            
200            
250            
300            
350            
400            
450            
500            
550            
600            
650            
700            
750            
800            
850            
900            
950            
1000            
             
             
             
             
             
             
             

  1. Calculate the Power produced through the Primary Coil and Secondary Coil for each resistance. Enter the values into the Data/Analysis Table.

  2. Enter the values for the Power Dissipated in the Secondary Coil and the Resistance into the "Secondary Power" Data Table in DataStudio.

  3. Maximize the "Secondary Power" graph.

  4. Determine the region on the graph that produces the maximum power.

  5. In order to more closely pinpoint the peak of the Power v. Resistance graph, repeat all of the steps from the Data Collection Procedure and steps 1-4 from the Analysis section using more resistance values above and below the suspected peak value.

  6. Enter the values of the Voltage and Current from the Secondary Coil into the "Secondary Voltage v. Current Data Table."

  7. Maximize the "Secondary Voltage v. Current" graph. (Note: For both data tables it is unnecessary to re-order the values from lowest to highest since the "Connect Data Points" feature has been turned off on both graphs.)

  8. In the "Secondary Voltage v. Current" graph, use the linear option of the button to record the slope and vertical intercept.

  9. In the "Secondary Power" graph, use the button to record the peak power.

  10. Disassemble the Secondary Coil.

  11. Use the Multi-meter to record the resistance of the Secondary Coil.
  1. Relate the values of the voltages from the Secondary Coil to the values of the voltages from the Primary Coil. Describe how this phenomenon is possible.

  2. At any point, is the power from the Secondary Coil ever greater than the power from the Primary Coil? Explain.

  3. What is the physical meaning of the slope of the Secondary Voltage v. Current graph?

  4. What is the physical meaning of the vertical intercept of the Secondary Voltage v. Current graph?

  5. Create an equation that relates the value of the slope of the Secondary Voltage v. Current graph, the resistance of the Secondary Coil and the resistance that corresponds to the peak power from the Secondary Power graph.

  6. What conditions are necessary to produce the peak power from the Secondary Power graph? Explain.

  7. The Primary Coil contains 235 turns while the Secondary Coil contains 2920 turns. For this experiment, what is the maximum theoretical voltage possible across the Secondary Coil? Explain.

  8. What effect would removing the core produce? Explain.

  9. What effect would inserting the Primary Coil only half-way into the Secondary Coil produce? Explain.