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What is an electron volt 'eV'?

 

  •  eV is abbreviated as “electron-Volt”.
  • Electron Volt is a simplified unit of energy.
  • We know that joule ‘J’ is the S.I unit of energy. But why do we use eV then? Let’s see.
  • The basic definition of an electron volt is, ‘It is the energy that an electron gains when it travels through a potential of one volt'.
  • The energy associated with an electron is measured in small unit called eV.
  • For an understanding, let us consider a parallel plate capacitor with positive charged plate on the left  side and the negative charged plate on the right side connected by a battery of 1V potential difference.
  • Consider an electron on the side of a negatively charged plate which is attracted to the positive charged plate due to electrostatic force. 
  • Therefore a kinetic energy is created when the electron moves from plate A to B.
  • This kinetic energy is measured as one electron volt.
  • 1eV means 1.6 x 10^-19 coulomb x 1 volt or just 1.6 X 10^-19 Joule.
Though we have the S.I unit of energy which is joules, we often use eV as the unit of energy for our convenience.  The need of eV is in many fields such as electronics, atomic, nuclear, particle physics, etc. It the measurement of energy in small units as we measure distance in cm, mm, etc instead of the S.I unit metre for an example.

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