Identify the physical quantity that cannot be measured using...

A spherometer is a device used for measuring the curvature of surfaces, particularly the radius of curvature of spherical or cylindrical surfaces. It consists of a central leg with a fine screw, and three outer legs that form a tripod. The device is primarily designed for measuring dimensions related to curved surfaces.

Specific rotation is a property related to the rotation of plane-polarized light in a substance. It is not measured using a spherometer. Instead, a polarimeter is typically used to measure specific rotation.