MCAT Physics Question 87: Answer and Explanation
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Question: 87
12. In the figure below, six currents meet at point P. What is the magnitude and direction of the current between points P and x?
- A. 2 A, toward x
- B. 2 A, toward P
- C. 10 A, toward x
- D. 10 A, toward P
Correct Answer: A
Explanation:
Kirchhoff's junction rule states that the sum of all currents directed into a point is always equal to the sum of all currents directed out of the point. The currents directed into point P are 8 A, 2 A, and 3 A, so the sum is 13 A. The currents directed out of point P are 5 A and 6 A, so the total is 11 A. Because the two numbers must always be equal, an additional current of 2 A must be directed away from point P toward point x.