MCAT Physics Question 67: Answer and Explanation
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Question: 67
7. The negative charge in the figure below (-1 μC) moves from y = -5 to y = +5 and is made to follow the dashed line. What is the work required to move the negative charge along this dashed line?
- A. –10 J
- B. -5 J
- C. 0 J
- D. 10 J
Correct Answer: C
Explanation:
There will be work done in moving the negative charge from its initial position to y = 0. However, in moving the negative charge from y = 0 to the final position, the same amount of work is done but with the opposite sign. This is because the force changes direction as the electron crosses y = 0. Therefore, the two quantities of work cancel each other out. This argument depends crucially on the symmetry of the initial and final positions.