A2L Item 256

• Description: Indicate the direction of the electric field at the origin due to 4 charges.
• Goal: Hone the vector nature of the electric field
• Source: CTQ283-6
• Keywords: Electromagnetism, Electric Field

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The question for students:

Four charges are positioned as shown. What is the direction of the electrical field at the origin?

1. Along i or in the +x direction
2. Along -i or in the -x direction
3. Along j or in the +y direction
4. Along -j or in the -y direction
5. Along some other direction
6. E=0 at the origin

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Commentary for teachers:

Answer

(6) Difficulty with this question usually indicates that students are not familiar with vectors. Good follow up question: ask whether it matters if the charges are along a 45 degree line.

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