A voltmeter is an instrument used for measuring the electrical potential difference between two points in an electric circuit. 伏特計是用於測量電路中兩點之間電勢差的儀器。
If a small potential difference exists between two ground points, some ground currents may flow through a sensitive part of the system. 如果在兩個接地點存在一個小的電勢差，在系統的敏感部分就會有接地電流通過。
Frequently, there is a small difference in potential between the ground points. 在各個接地點之間常常會存在一個很小的電位差。
The polarization is proportional to the deformation and causes an electric potential difference over the crystal. 極化與變形時成比例的且能形成晶體內不同的電位差。
