Why does the point experience NEGATIVE field strength?

  • #1
Hi, i'm looking for an explanation to this answer of a past paper that I'm doing, it's from OCR (A level) G485, question 1 b ii)

the question on top, and answer on bottom


i don't understand why would the point experience a negative electric field strength when it's getting closer to a positive source or vice versa (positive field strength) , this is the first question of the paper, and not much other relevant information is presented... what am i not understanding?

http://www.ocr.org.uk/Images/243747-question-paper-unit-g485-01-fields-particles-and-frontiers-of-physics.pdf [Broken]

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Answers and Replies

  • #2
At point X , the magnitude of the resultant electric field strength due to the particles A and B is zero
That is an important part of the question.

The sign gives the direction. If you are close to one of the charges, the influence of this charge dominates, but to the left of X you are on the right side of the charge A, to the right of X you are on the left side of charge B. The direction towards the charge is different, and a different direction means a different sign.
  • #3
i didn't notice! thanks

i even drew out the diagrams and i still didn't caught that, thanks

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