10. Consider a uniformly polarized dielectric sphere where the polarization inside the sphere is . Find the displacement ficld inside the sphere.
(A)0
(B)
(C)
(D)

6. In the static case, consider an interface between the free space and a perfect conductor with some charges on the surface. Which of the following statements is not correct? (A) The electric field in the free space near the surface is proportional to the surface charge density. (B) There is no electric field in the conductor. (C) The surface charge would experience no electric force. (D) The electric potcntial is the same in the conductor, even near sharp edges.

7.An uncharged metal sphere is placed in an otherwise uniforn electric field . Find the induced surface charge density. (A) Zero everywhere on the sphere. (B) ε0E0cosθ (C) 2ε0E0cosθ (D) 3ε0E0cosθ

8.What does ρ in the Gauss's lawmean? (A) The free volume charge density. (B) The free surface charge density. (C) The sum of the polarization volume charge density and the free voiume charge density. (D) The sum of all surface charge density and volume charge density.

9.What does in the Ampcre's lawmean? (A) The free volume current density. (B) The free surface current density. (C) The sum of the polarization current density, the magnetization current density, and the free current density. (D) The sum of all surface current density and volume current density.

11. A short solenoid (length I, radius a, ni turns per unit length) lies on the axis of a very one solenoid (length /, radius b, na turns per unit length), where a＜b. What is the total magnetic flux through the long solenoid if a steady current / flows in the short aD solenoid? (A) μ0πa2n1n2ll (B) μ0πb2n1n2ll(C) μ0πa2n12ll(D)μ0πabn1n2ll

12. Which of the following statements is not correct in general? (A) Diamagnetism could be related to the orbital motion of electrons. (B)Paramagnetism could be related to the electronic spin. (C) Ferromagnetism becomes obvious above the Curie temperature. (D) Antiferromagnetism vanishes above the Neel temperature.

13. Consider a sheet current source at z = 0. The medium on either side of the sheet is free space. Which of the following statements for the region z ＞0 is not correct? (A) There will be a wave propagating in the +z direction. (B) The electric field and magnetic field are in phasc. (C) The instantaneous power flow out of an arbitrary closed surface is zero. (D) The average power flow is half of the peak power flow.

14. Consider a sheet current source at z =0. The medium on either side of the sheet is perfect dielectric. Assume the dielectric constant is higher in the z ＞0 region. Which of the following statcments is not correct? (A) The power flux is higher in the z＞0 region. (B) The power flux is higher in the z ＜0 region. (C) The power flux is the same in both regions (D) There is no power flux in both regions.

15. Assume the relation holds in a medium, where ε is a constant. What do we not imply for that medium? (A) The medium is linear. (B) The medium is isotropic. (C) The medium is nondispersive. (D) The medium is lossless.

複選題16. Assume two electromagnetic waves (frequency fA and fB) enters a nonlinear material whose polarization field includes a term that is proportional to the square of the clectric field. Which of the following frequencies could one possibly observe at the output of the nonlincar material? (A) fA+ fB(B) 2fA (C) 2fB (D) All of the above.