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Unformatted text preview: Munoz (gm7794) – HW02 – TSOI – (92515) 1 This printout should have 16 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points The diagrams below depict three electric field patterns. Some of these patterns are physi cally impossible. Assume these electric field patterns are due to static electric charges outside the regions shown. (a) (b) (c) Which electrostatic field patterns are phys ically possible? 1. (b) and (c) 2. (a) and (c) 3. (a) and (b) 4. (a) only 5. (c) only 6. (b) only correct Explanation: Electrostatic lines of force do not intersect one another. Neither do they form a closed circuit (unless there is a changing magnetic field present). 002 10.0 points Given symmetrically placed rectangular insu lators with uniformly charged distributions of equal magnitude as shown in the figure. x y + + + + + + + + + + + +     In this figure, at the origin, the net field % E net is 1. zero and the direction is undefined. 2. along 30 ◦ direction in the first quadrant. 3. aligned with the positive xaxis. 4. aligned with the negative yaxis. correct 5. along 225 ◦ direction in the first quad rant. 6. aligned with the negative xaxis. 7. along 60 ◦ direction in the first quadrant. 8. along 135 ◦ direction in the first quad rant. 9. aligned with the positive yaxis. 10. along 45 ◦ direction in the first quadrant. Explanation: At the origin the fields from the bottom slab points towards the negative y axis (towards the negatively charged slab). The field from the right and left slabs have equal magnitudes at the origin and are sym Munoz (gm7794) – HW02 – TSOI – (92515) 2 metric about the y axis. The field from the right and left slabs point away from each pos itively charged slab. Therefore the x compo nent of the field cancels at the origin. The net field from the right and left slabs points towards the negative y axis (away from the positively charged slab). Hence, the sum of the electric fields from all three slabs is aligned with the negative yaxis. 003 (part 1 of 2) 10.0 points A dipole (electrically neutral) is placed in an external field. + (a) + (b) + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + (c) (d) For which situation(s) shown above would the net force on the dipole be equal to zero? 1. ( b ) only 2. ( a ) and ( b ) 3. ( c ) only 4. ( a ) only 5. ( a ) and ( d ) 6. ( b ) and ( d ) 7. ( c ) and ( d ) correct 8. ( d ) only 9. ( b ) and ( c ) 10. ( a ) and ( c ) Explanation: The force on a charge in the electric field is given by % F = q % E and the torque is defined as % T = %r × % F Δ % E = k Δ q r 2 ˆ r % E = Δ % E i ....
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This note was uploaded on 06/10/2011 for the course PHY 302l taught by Professor Morrison during the Summer '08 term at University of Texas at Austin.
 Summer '08
 morrison
 Physics, Charge

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