A2L Item 257

• 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: CTQ283-7
• 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 -j or in the -y direction
3. Along j or in the +y direction
4. Along -i or in the -x direction
5. Along some other direction
6. E=0 at the origin

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Commentary for teachers:

Answer

(3) Difficulty with this question indicates that students do not know how the direction of the electric field relates to the sign of the charge.

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