15. In the question 16 above, at what angle from the x-axis the principal normal stresses will occur? 16. In this experiment how many strain gages are used on the Wheatstone bridge circuit? a. 1 active and 3 compensatory b. 2 active and 2 compensatory c. 3 active and 1 compensatory d. 4 active and 0 compensatory 17. How shear strain is measured using strain gages? a. Placing the strain gage at an angle 90 to the direction of shear stress b. Placing the strain gage at an angle 45 to the direction of shear stress c. Placing the strain gage parallel to the direction of shear stress d. All of the above