Summarizing Electric Potential Energy: Potential Difference

Summary

• Electric potential is potential energy per unit charge.
• The potential difference between points A and B, \({V}_{B}–{V}_{A}\), defined to be the change in potential energy of a charge \(q\) moved from A to B, is equal to the change in potential energy divided by the charge, Potential difference is commonly called voltage, represented by the symbol \(\text{Δ}V\).

  \(\Delta V=\cfrac{\text{ΔPE}}{q}\phantom{\rule{0.25em}{0ex}}\text{and ΔPE =}\phantom{\rule{0.25em}{0ex}}q\Delta V\text{.}\)

• An electron volt is the energy given to a fundamental charge accelerated through a potential difference of 1 V. In equation form,

  \(\begin{array}{lll}\text{1 eV}& =& (1.60×{\text{10}}^{\text{–19}}\phantom{\rule{0.25em}{0ex}}\text{C})(1 V)=(1.60×{\text{10}}^{\text{–19}}\phantom{\rule{0.25em}{0ex}}\text{C})(1 J/C)\\ & =& 1.60×{\text{10}}^{\text{–19}}\phantom{\rule{0.25em}{0ex}}\text{J.}\end{array}\)

• Mechanical energy is the sum of the kinetic energy and potential energy of a system, that is, \(\text{KE}+\text{PE}.\) This sum is a constant.

Glossary

electric potential

potential energy per unit charge

potential difference (or voltage)

change in potential energy of a charge moved from one point to another, divided by the charge; units of potential difference are joules per coulomb, known as volt

electron volt

the energy given to a fundamental charge accelerated through a potential difference of one volt

mechanical energy

sum of the kinetic energy and potential energy of a system; this sum is a constant