Introduction to Process Control

Work the problems below. To receive any credit, you must show all work. You may submit your work in a word processing document or in a pdf file. Graphic files are not acceptable submissions. Your file submission document should be entitled Week1AYourGID (replace YourGID with your specific GID).

1. A sensor has a linear resistance change of 100 to 195 ohms, as temperature changes from 20o – 120oC. Find the I/O relationship.

2. Using the equation for modeling a 1st order response, find the time it takes for a sensor to reach 90% of it final value given a final sensor output of 4.0V, an initial sensor output of 2.0V, and a time constant = 0.0025/s.

3. A 1000 ohm resistor is measured 10 times and the following readings were taken in the table below.

a. Find the mean and standard deviation of the measurements.

b. Assuming a normal distribution, there is a 99.7% probability that the true value of the resistance falls between what two values?

4. The following unbalanced Wheatstone Bridge is constructed. Calculate the output voltage across points C and D and the value of resistor R4 required to balance the bridge circuit.

5. Refer to the op amp below (Fig. 2.26 in your text). If Vin = 0.5V, R1 = 10k ohm, and R2 = 25k ohm, calculate:

a. the output voltage, Vout,

b. the current in the 10k ohm resistor.

c. What would be the use or purpose of such a circuit? And how do your results demonstrate that?