Vernier calipers can measure lengths less than 1 cm, but the accuracy diminishes significantly at smaller measurements. The inherent error of a standard mm scale can lead to inaccuracies of +/- 1mm, which is unacceptable for precise physics experiments. While a vernier scale improves accuracy to +/- 0.1mm, this may still be insufficient for measurements under 10mm. For greater precision in such cases, alternative instruments like micrometers or traveling microscopes are recommended. Ultimately, the choice of measuring tool depends on the required accuracy for the specific application.