24) This problem asks us to find the direction of the net electric force produced by the +2 and -2 microcoulomb charges. I am going to start by looking at Coulomb's law for electric force.
The problem states that the charges are placed on the corners of an equilateral triangle. This means that the distance between the charges will be constant. Also, since the same magnitude charges are involved, the force produced by both charges will have the same magnitude. However, they may point in different directions, as indicated by the different signs in the +2 microcoulomb and -2 microcoulomb charges.
Next, we can draw the forces out.
Since like charges repel, the F[+2] tries to push the +1 microcoulomb charge away. On the other hand, since unlike charge attract, the F[-2] tries to pull the +1 microcoulomb charge closer. I drew the individual x and y-components of the forces to illustrate that the F[+2y] and F[-2y] are the same magnitude, but point in opposite directions. This means these forces will cancel out. However, the F[+2x] and F[-2x] point in the same direction, so their magnitudes can be added together. The x-components of the two forces will sum to look like this.
Answer: E
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