The change in electric potential energy is related to the work done by the elect

Question

The change in electric potential energy is related to the work done by the electric force (see Section 6.1). The force on the positive charge is in the same direction as the electric field, and the displacement of the charge is opposite to the direction of the force. What does this tell you about whether the work is positive or negative?


A positive charge is moving from point A to point B in a uniform electric field, as shown in the drawing. The electric force does __________ work on the charge and, as a consequence, its electric potential energy __________ .




positive, decreases

negative, increases

negative, does not change

negative, decreases

positive, increases

Explanation / Answer

Electric fields originate on positive charges and move towards negative charges, and since we know that the charge moves in the direction of the electric field, that it is being repelled by the positive charge and is a positive charge itself. This also means that the electric force is in the same direction as the electric field in this case on the positive charge. Since the charge moves in the same direction as the force, the work done by the electric field is POSITIVE Since the positive charge is moving in the direction of a negative charge, its potential energy is DECREASING So the answer is A

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