玉米珍
AP® Physics C: Electricity and Magnetism
2008 Free-Respon Questions
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PHYSICS C: ELECTRICITY AND MAGNETISM
SECTION II
Time-45 minutes
3 Questions
Directions: Answer all three questions. The suggested time is about 15 minutes for answering each of the questions, which are worth 15 points each. The parts within a question may not have equal weight. Show all your work in the pink booklet in the spaces provided after each part, NOT in this green inrt.
2008E1. A metal sphere of radius a contains a charge +Q and is surrounded by an uncharged, concentric, metallic shell of inner radius b and outer radius c, as shown abov
微信怎么加群找群e. Express all algebraic answers in terms of the given quantities and fundamental constants.
(a) Determine the induced charge on each of the following and explain your reasoning in each ca.
i. The inner surface of the metallic shell
ii. The outer surface of the metallic shell
(b) Determine expressions for the magnitude of the electric field E as a function of r, the distance from the center of the inner sphere, in each of the following regions.
i. r < a
ii. a < r < b
iii. b < r < c
iv. c < r
(c) On the axes below, sketch a graph of E as a function of r.
(d) An electron of mass me carrying a charge –e is relead from rest at a very large distance from the spheres. 杜甫自称Derive an expression for the speed of the particle at a distance 10c from the center of the spheres.*
*=In the original printed version, the distance was given as “10 r”.
2008E2. In the circuit shown above, A and B are terminals to which different circuit components can be connected.
(a) Calculate the potential difference across R2 immediately after the switch S is clod in each of the following cas.
i. A 50 Ω resistor connects A and B.
ii. A 40 mH inductor connects A and B.
iii. An initially uncharged 0.80 µF capacitor connects A and 夹睫毛B.
(b) The switch gets clod at time t = 0. On the axes below, sketch the graphs of the current in the 100 Ω resistor R3 versus time t for the three cas. Label the graphs R for the resistor, L for the inductor, and C for the capacitor.
Figure 1
2008E3. The circular loop of wire in Figure 1 above has a radius of R and carries a current I. Point P is a distance of R/2
above the center of the loop. Express algebraic answers to parts (a) and (b) in terms of R, I, and fundamental constants.
(a)
i. State the direction of the magnetic field B1 at point P due to the current in the loop.
ii. Calculate the magnitude of the magnetic field B1 at point P.
Figure 2 Figure 3
A cond identical loop also carrying a current I is added at a distance of R above the first loop, as shown in Figure 2 above.
(b) Determine the magnitude of the net magnetic field Bnet at point P.
A small square loop of wire in which each side has a length s is now placed at point P with its plane parallel to the plane of each loop, as shown in Figure 3 above. For parts (c) and (d), assume that the magnetic field between the two circular loops is uniform in the region of the square loop and has magnitude Bnet.
(c) In terms of B威客网赚>讲笑话net and s, determine the magnetic flux through the square loop.
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(d) The square loop is now rotated about an axis in its plane at an angular speed . In terms of Bnet, s, and , calculate the induced emf in the loop as a function of time t, assum
ing that the loop is horizontal at t = 0 .
