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Two negatively charged objects A and B are charged and create an electric field. The electric field strength at a point precisely midway between these two charges is 10 N/C, directed leftward. This provides evidence that ____.
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The electric field strength (E) at a given location about a source charge is dependent upon the quantity of charge on the source charge (Q) and the distance that the location is from the source (d). The dependency between electric field strength, the quantity of charge on the source charge, and the distance from the source is expressed by the equation
E = k • Q / d2
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Direction of Electric Field:
The electric field direction at a location about a source charge is the direction which a positive test charge would be pushed or pulled when placed at that location.
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In this question, the net electric field at a location which is equidistant from two like-charged sources is shown. The net electric field vector is the vector sum of the two electric field vectors created by the individual sources. That is, Enet=EA+EB. Since there is a net electric field, the two source charges must be creating electric fields with unequal magnitudes; as such they do not cancel when added as vectors. So we know that EA is not equal to EB.
The magnitude of an electric field is dependent upon the distance from the source and the quantity of charge on the source (see Formula Frenzy section). Since the location under consideration is equidistant from both sources, distance must not be the reason that A and B create electric fields of unequal strength. So the cause of the unequal strength fields is that A and B have a different quantity of charge. If the net electric field is to the left, then whichever object creates the leftward field must be creating the stronger field. And if the net electric field is to the right, then whichever object creates the rightward field must be creating the stronger field.
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