34. A 16-nC charge is distributed uniformly along the x axis from x = 0 to x = 4 m. Which of the following integrals is correct for the magnitude (in N/C) of the electric field at x = +10 m on the x axis? 
(A)
(B)
(C)
(D)

30. A tube open at one end and closed at the other end produces sound having a fundamental frequency of 350 Hz. If you now open the closed end, the fundamental frequency becomes (A) 87.5 Hz. (B) 175 Hz. (C) 350 Hz. (D) 700 Hz. (E) 1400 Hz.

31. A solid nonconducting sphere of radius R carries a charge Q distributed uniformly throughout its volume. At a certain distance r1 (r1 ＜ R) from the center of the sphere, the electric field has magnitude E. If the same charge Q were distributed uniformly throughout a sphere of radius 2R, the magnitude of the electric field at the same distance r1 from the center would be equal to (A) E/8. (B) E/2.(C) 2E.(D) 8E. (E) E.

32. Determine the energy stored in C2 when C1 = 15 MF, C2 = 10 MF, C3 = 20 uF, and V0 = 18 V. Xx (A)0.72 mJ (B)0.32 mJ (C)0.50 mJ (D)0.18 m.J (E)1.60 mJ

33. A charge per unit length given by λ(x) = bx, where b = 12 nC/m2, is distributed along the x axis from x = +9.0 cm to x = +16 cm. If the electric potential at infinity is taken to be zero, what is the electric potential at the point P on the y axis at y = 12 cm? (A)5.4 V (B)7.2 V (C)9.0 V (D)9.9 V (E) 16 V

複選題35. The electric field in the region of space shown is given by ㆍ N/C where y is in m. What is the magnitude of the electric flux through the top face of the cube shown?  (AB) 90 N ㆍm2/C (AC) 6.0 N ㆍ m2/C (AD)54 Nㆍ m2C (AE)12 Nㆍ m2/C (BC) 126Nㆍ m2/C (BD)一律送分

36. A charge per unit length given by 1(x) = bx, where b = 12 nC/m2, is distributed along the x axis from x= t9.0 cm to x= +16 cm. If the electric potential at infinity is taken to be zero, what is the electric potential at the point P on the y axis at y = 12 cm? (A)5.4 V (B)7.2 V (C)9.0 V (D)9.9 V (E) 16 V

37. When a cube is inscribed in a sphere of radius r, the length L of a side of the cube is L = . If a positive point charge Q is placed at the center of the spherical surface, the ratio of the electric flux Qsphere at the spherical surface to the flux Qcbe at the surface of the cube is(A)(B)(C) 1(D)(E)

38. For the potential Y = 3x2z - 2yz3, what is the corresponding electric field at the point (2,2,2)?(A)(B) (C) (D)  

39. A square loop (L = 0.20 m) consists of 50 closely wrapped turns, each carrying a current of 0.50 A. The loop is oriented as shown in a uniform magnetic field of 0.40 T directed in the positive y  direction. What is the magnitude of the torque on the loop?(A) 0.21 Nㆍm(B) 0.20 N ㆍm (C) 0.35Nㆍm(D) 0.12 N ㆍm(E) 1.73 N ㆍm

40. A bar magnet is dropped from above and falls through the loop of wire shown below. The north pole of the bar magnet points downward towards the page as it falls. Which statement is correct?  (A) The current in the loop always flows in a clockwise direction. (B) The current in the loop always flows in a counterclockwise direction. (C) The current in the loop flows first in a clockwise, then in a counterclockwise. direction. (D) The current in the loop flows first in a counterclock wise, then in a clockwise. direction. (E) No current flows in the loop because both ends of the magnet move through the. loop