1 of 3 FieldsII - 1. What the magnitude of the vector ˆˆˆˆ(i j) (x y)−=−? A) 1 B) 2 C) 0 D) Some other number. E) No answer, because is not a vector. ˆˆ(x y)− Answer: Some other number. The magnitude of the vector is 2. FieldsII - 2. There are no charges inside the regions shown. Which of the following are possible electric field line configurations? (a) (b) (c) A: (a) only B: (b) only C: (c) only D: None are possible E: Some other answer (all, a and b only, etc.) Answer: Some other answer: (a) and (c) are possible field line diagrams.9/11/2009 PHYS1120 Dubson Fa09 ©University of Colorado2 of 3 FieldsII - 3. Consider the four electric field line patterns shown. Assume that that are no charges in the regions shown. Which, if any, of the patterns represent possible electrostatic fields. A: All are possible. B: II only C: II and III only D: None are possible. E: None of the above. IV III II I Answer: II only.9/11/2009 PHYS1120 Dubson Fa09 ©University of Colorado3 of 3 FieldsII - 4. From the figure, what can you say about the magnitude of the charge on the bar Qbar, compared to the magnitude of the charge Q of the positive point charge? + + Q Qbar A: QQbar> B: QQbar= C: QQbar< From the figure, what can you say about the net charge on the bar? A: Qbar = 0 B: Qbar > 0 (that is, the bar has a net positive charge) C: Qbar < 0 (the bar has a net negative charge) D: Not enough information in the figure to answer the question. Answers: Qbar< Q, Qbar < 0 FieldsII - 5. Two infinite planes are uniformly charged with the same charge per area σ. If one plane only were present, the field due to the one plane would be E. The field in region B has magnitude… ++++++++++++++++++++++++++++++++++ ++++++++++++++++++++++++++++++++++ A B C A: zero B: E C: 2E D: depends on exact position. The field in region A has magnitude… A: zero B: E C: 2E D: depends on exact position. Answers: in region B, the field has magnitude zero. in region A, the field has magnitude 2E. 9/11/2009 PHYS1120 Dubson Fa09 ©University of
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