3.3.4: Procedure

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1. A typical potentiometer is shown in Figure 9.3.1. Using a 10 k pot, first rotate the knob fully counterclockwise and using the DMM, measure the resistance from terminal A to the wiper arm, W. Then measure the value from the wiper arm to terminal B. Record these values in Table 9.5.1. Add the two readings, placing the result in the final column.

2. Rotate the knob 1/4 turn clockwise and repeat the measurements of step 1. Repeat this process for the remaining knob positions in Table 9.5.1. Note that the results of the final column should all equal the nominal value of the potentiometer.

3. Construct the circuit of Figure 9.3.2 using E = 10 volts, a 10 k potentiometer and leave \(R_L\) open. Rotate the knob fully counter-clockwise and measure the voltage from the wiper to ground. Record this value in Table 9.5.2. Continue taking and recording voltages as the knob is rotated to the other four positions in Table 9.5.2.

4. Set \(R_L\) to 47 k and repeat step 3.

5. Set \(R_L\) to 4.7 k and repeat step 3.

6. Set \(R_L\) to 1 k and repeat step 3.

7. Using a linear grid, plot the voltages of Table 9.5.2 versus position. Note that there will be four curves created, one for each load, but place them on a single graph. Note how the variance of the load affects the linearity and control of the voltage.

8. Construct the circuit of Figure 9.3.3 using E = 10 volts, a 100 k potentiometer and \(R_L\) = 1 k. Rotate the knob fully counter-clockwise and measure the current through the load. Record this value in Table 9.5.3. Repeat this process for the remaining knob positions in Table 9.5.3.

9. Replace the load resistor with a 4.7 k and repeat step 8.