Does U=qV or -qV? I notice my textbook uses qV but

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SUMMARY

The correct expression for electric potential energy is U=qV, as confirmed by multiple participants in the discussion. While some resources may present U=-qV for conceptual clarity, this is not the standard convention. The negative sign in U=qV is inherently accounted for when considering the direction of force acting on a charge in an electric field. Understanding the distinction between potential energy and force is crucial for accurate problem-solving in electrostatics.

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  • Understanding of electric potential energy (U)
  • Familiarity with electric fields (E) and forces (F)
  • Knowledge of charge (q) and voltage (V) relationships
  • Basic principles of electrostatics
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  • Explore the implications of moving charges in electric fields
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Students of physics, educators teaching electrostatics, and anyone seeking to clarify concepts of electric potential and energy in electrostatics.

belledona
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Hi I have a question about electric potential! Since the negative sign isn't used in U=qV, and a-b is used for subscripts, then that takes care of the negative. But what about using U=-qV? An online lecturer uses U=-qV, while my textbook uses U=qV and then uses -qV to explain the force used to move a charge AGAINST the electric field. I'm wondering if qV or -qV is convention, because -qV is easier for me to understand conceptually but I lose the negative sign sometimes during problems...

Thank you!
 
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U=qV is correct.

The force is different, so don’t get confused about that. The force on a positive charge points in the direction of decreasing potential.
 
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Dale said:
positive

Dale said:
U=qV is correct.

The force is different, so don’t get confused about that. The force on a positive charge points in the direction of decreasing potential.
hi, thanks for your answer! so U=qV would only be negative if F=qE --> q=F/E (force is negative) here?
 
Essentially yes, but the way you wrote it is a bit sloppy. To make it correct you would need to say:

The change in U=qV would be negative if q moves in the direction of F=qE here?
 

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