The gap under the straightedge should be measured at which location?

The gap under the straightedge should be measured at which location?

• A. Between the Two High Spots Where the Straightedge Rests
• B. At the Left End
• C. In the Center of the Span
• D. At the Highest Spot

Answer: (A)

When using a straightedge to check flatness, the tool is supported on two high spots of the surface. The gap you record is the clearance under the straightedge in the span between those two supports—the area midway between them. That location shows the actual sag of the surface relative to the straightedge. Measuring at the ends or at a high spot wouldn’t reflect the true deviation, since those points are either in contact or outside the span where the gap isn’t representative. So, the gap should be measured between the two high spots where the straightedge rests.

When using a straightedge to check flatness, the tool is supported on two high spots of the surface. The gap you record is the clearance under the straightedge in the span between those two supports—the area midway between them. That location shows the actual sag of the surface relative to the straightedge. Measuring at the ends or at a high spot wouldn’t reflect the true deviation, since those points are either in contact or outside the span where the gap isn’t representative. So, the gap should be measured between the two high spots where the straightedge rests.