Work done per unit charge by electric field on charge

AI Thread Summary
The discussion focuses on determining the work done by an electric field on a charge, emphasizing the relationship between force, displacement, and electric potential. It clarifies that work is positive when the force and displacement are in the same direction. The electric field lines indicate that they point from high to low potential, aligning with the direction of force acting on a positive charge. Understanding these concepts is crucial for solving related problems in physics. The conversation concludes with an affirmation of the correct interpretation of these principles.
Cicicicici
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Homework Statement


Screen Shot 2018-05-25 at 2.37.17 pm.png


Homework Equations

The Attempt at a Solution


I know the units for V is J/C so #3 and #4 are wrong. But how do I determine the signs?
 

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Is the work done by the electric field positive or negative? What do you need to ascertain in order to answer this question? Hint: When is the work done by a force positive and when is it negative?
 
kuruman said:
Is the work done by the electric field positive or negative? What do you need to ascertain in order to answer this question? Hint: When is the work done by a force positive and when is it negative?
Work is positive when force is in same direction as displacement. So here the direction is X to Y and the force is also from X to Y because Vx>Vy?
 
Cicicicici said:
Work is positive when force is in same direction as displacement. So here the direction is X to Y and the force is also from X to Y because Vx>Vy?
Yes, electric field lines point from a region of high potential to a region of low potential. Since the charge is positive, the electric force on it is in the same direction as the electric field.
 
kuruman said:
Yes, electric field lines point from a region of high potential to a region of low potential. Since the charge is positive, the electric force on it is in the same direction as the electric field.
Thank you!
 
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