# Final exam practice-problems - pan(zp695 Final exam...

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pan (zp695) – Final exam practice – chiu – (56565) 1 This print-out should have 28 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. 001 10.0points An electron and a proton are placed at locations A and B respectively. At time t = 0, the electron begins to accelerate as shown, with the magnitude of acceleration being a . If e and m p are the charge and mass of a proton, r is the distance between A and B , θ is the angle shown in the figure and c is the speed of light, what will be the magnitude and direction of acceleration of the proton a moment after the electromagnetic waves from the electron reach B ? Note: Vector vectorr has magnitude r and di- rection pointing from A to B . Ignore the electrostatic force between the electron and the proton 1. 1 4 πǫ 0 e 2 a cos θ m p c 2 r , parallel to vectora 2. 1 4 πǫ 0 e 2 a sin θ m p c 2 r , parallel to vectorr 3. 1 4 πǫ 0 e 2 a sin θ m p c 2 r , perpendicular to vectora 4. 1 4 πǫ 0 e 2 a sin θ m p c 2 r , perpendicular to vectorr 5. 1 4 πǫ 0 e 2 a cos θ m p c 2 r , parallel to vectorr 6. 1 4 πǫ 0 e 2 a cos θ m p c 2 r , perpendicular to vectora 7. 1 4 πǫ 0 e 2 a cos θ m p c 2 r , perpendicular to vectorr 8. 1 4 πǫ 0 e 2 a sin θ m p c 2 r , parallel to vectora 002 10.0points Two long sheets of width L = 2 . 2 cm each contain N = 220 closely-packed wires car- rying current I = 12 μ A in opposite direc- tions. The sheets are separated by a distance h = 174 μ m. Letting the positive x -direction be to the right, calculate the magnitude of vector B at point A located y = 48 μ m above the exact center of the lower sheet. Answer in units of T 003(part1of2)10.0points The switch below is initially set at position b . There is no charge nor current around the right loop while at position b . At t = t 0 the switch is set to position a . L R C E S b a c d What is the potential difference V dc V c V d across the resistor R at t = t 0 ? 1. V dc = 2. V dc = 0 3. V dc = E e 1 4. V dc = E (1 e 1 ) 5. V dc = −E
pan (zp695) – Final exam practice – chiu – (56565) 2 6. V dc = −E e 1 7. V dc = E 8. V dc = −E (1 e 1 ) 9. V dc = −∞ 10. V dc = E e 004(part2of2)10.0points After a long time at position a , the switch is set back to position b . Denote this time as t = 0. What is the maximum energy stored in the capacitor, expressed in terms of L , E , and R ? (Hint: Use conservation of energy.) A very long glass rod of length 2 R carries a uniformly distributed charge + q as shown in the figure. A very large plastic disk of radius R , carrying a uniformly distributed charge Q is located at a distance d from the rod, where d << R . Determine the potential difference Δ V rod = V B V A due to the long rod alone.