A2L Item 203

Goal: Reason regarding electric fields

Source: 283 –

Charge, Q, is at the origin. Points A-E are positions where other
charges may be present. Etotal at point F is non-zero and
points in the +i direction. Which of the following situations
could account for this?

  1. Another charge is present at position
    A.
  2. Two other charges are present at C & D.
  3. Two other
    charges are present at D & B.
  4. Two other charges are present at
    E & A.
  1. A only
  2. B only
  3. C only
  4. D only
  5. A and B
  6. A, C and D
  7. A, B, and D
  8. A, B, C, and D

Commentary:

Answer

(2) Only a charge at C can counter the y component of the field of Q at
F. A charge at B or D can then create a field at F that points in the i
direction.