Tensile strain can be determined from the variation in electrical resistance of a device known as a strain gauge. A strain gauge is made of a folded fine metal wire fixed onto a flexible insulating backing sheet. The strain gauge is attached securely to the specimen. As the strain in the specimen increases, what happens to the resistance of the wire?
- AIt decreases, because the length decreases and the cross-sectional area increases.
- BIt decreases, because the length increases and the cross-sectional area decreases.
- CIt increases, because the length decreases and the cross-sectional area increases.
- DIt increases, because the length increases and the cross-sectional area decreases.