6. An infinitely long, straight conducting wire with a circular cross section of radius $b$ carries a steady current $I$ that is flowing upward (along the $\hat{\mathbf{z}}$ direction). Which of the following statements is correct?
(A) Viewing from the top the magnetic field $\pmb{B}$ is circulating clockwise around the wire.
(B) Inside the wire, the magnitude of the magnetic field $|\pmb{B}|$ at a point of interest scales linearly with the distance of that point away from the center of the wire.
(C) Outside the wire, the magnitude of the magnetic field $|\pmb{B}|$ at a given point decreases with the square of its distance from the center of the wire.
(D) None of the above is correct.

7. A metal bar slides over a pair of conducting rails in a uniform magnetic field $\mathbf{B} = B_{0}\hat{\mathbf{z}}$ with a constant velocity $\mathbf{u}$. A load with resistance of $R$ is connected to nodes 1 and 2. Which of the following statements is correct? (A) Each electron in the moving bar experiences a unit force that has a magnitude of $|\mathbf{u}|B_0$ and is pointing in the $-y$ direction. (B) Before connecting the load, an open-circuit voltage $V_{0} = -|\mathbf{u}|B_{0}h$ is generated. (C) After connecting the load, the current will flow counterclockwise. (D) None of the above.

8. Which of the following equations describes charge conservation? (A) $\nabla \times \mathbf{E} = -\frac{\partial \mathbf{B}}{\partial t}$ (B) $\nabla \cdot \mathbf{D} = \rho$ (C) $\nabla \times \mathbf{H} = \mathbf{J} + \frac{\partial \mathbf{D}}{\partial t}$ (D) $\nabla \cdot \mathbf{J} = -\frac{\partial \rho}{\partial t}$

9. For electromagnetic waves propagating in conductors, we can derive the modified wave equation: $$ \nabla^{2} \mathbf{E} - \mu \epsilon \frac{\partial^{2} \mathbf{E}}{\partial t^{2}} - \mu \sigma \frac{\partial \mathbf{E}}{\partial t} = 0 $$ Consider a monochromatic plane wave as $\mathbf{E} = \mathbf{E}_0 e^{i(kz - \omega t)}$, where the wave number $k$ is a complex number. Please derive the expression for the wave number $k$. (A) $\omega \sqrt{\mu \epsilon} \left(1 + \frac{i\sigma}{\omega \epsilon}\right)^{\frac{1}{2}}$ (B) $i\omega \sqrt{\mu \epsilon} \left(1 + \frac{\sigma}{\omega \epsilon}\right)$ (C) $\omega \sqrt{\mu \epsilon} \left(1 + \frac{\omega \epsilon}{i\sigma}\right)^{1/2}$ (D) None of the above.

10. For plane electromagnetic waves propagating in vacuum, which one of the following descriptions is incorrect? Here $\mathbf{k}$ is the wave vector, and $\mathbf{S}$ is the Poynting vector. (A) $\mathbf{k} \perp \mathbf{E}$ (B) $\mathbf{S} \perp \mathbf{k}$ (C) $\mathbf{E} \perp \mathbf{H}$ (D) None of the above.

11. Consider a plane electromagnetic wave propagating in vacuum. The electric field is given by $\mathbf{E} = \mathbf{E}_0 e^{i(kx - \omega t)}$. The Poynting vector is labeled by $\mathbf{S}$. The intrinsic impedance $\eta$ (also called wave impedance) is $377\ \Omega$. The time-averaged Poynting vector $\langle S \rangle$ is $1\ \mathrm{W/m^2}$. Please calculate $E_0$, i.e., the amplitude of the electric field. Please choose the closest answer. (A) $54.2\ \mathrm{V/m}$ (B) $377\ \mathrm{V/m}$ (C) $19.4\ \mathrm{V/m}$ (D) $27.5\ \mathrm{V/m}$

12. Consider a plane electromagnetic wave expressed by its phasor form of $\mathbf{E} = \mathbf{E}_0 e^{i(k_x x + k_y y + k_z z)}$. The expression should satisfy the Helmholtz equation: $\nabla^2 \mathbf{E} + \omega^2 \mu \epsilon \mathbf{E} = 0$. As a result, which one of the following relations must be true? (A) $k_x + k_y + k_z = \omega \sqrt{\mu \epsilon}$ (B) $k_x^2 + k_y^2 + k_z^2 = \omega^2 \sqrt{\mu \epsilon}$ (C) $k_x^2 + k_y^2 + k_z^2 = \omega^2 \mu \epsilon$ (D) None of the above.

13. What is the short-circuit impedance measured at the input terminals of an infinitely long transmission line with the parameters of $(R = 45 \times 10^{-3}\ \Omega/\mathrm{m}, L = 27 \times 10^{-8}\ \mathrm{H/m}, G = 5 \times 10^{-5}\ \mathrm{S/m}, C = 3 \times 10^{-10}\ \mathrm{F/m})$ at $5\ \mathrm{GHz}$? (A) $30\ \Omega$ (B) $50\ \Omega$ (C) $75\ \Omega$ (D) None of the above. 

14. An 1-GHz voltage source $(V_{s})$ is applied to a short-circuit quarter-wavelength lossless transmission line as the figure shown below. The characteristic impedance of the transmission line is $20\Omega$. Please evaluate the current of $I_{x}$. (A) $0.25\mathrm{A}$ (B) $0.25\angle 90^{\circ}\mathrm{A}$ (C) $0.25\angle 270^{\circ}\mathrm{A}$ (D) None of the above.

15. Please select the closest dB value of the reflection coefficient of a $75 - \Omega$ resistive load in a $50 - \Omega$ system $Z_{0}$. (A) $-6.9\mathrm{dB}$ (B) $-13.9\mathrm{dB}$ (C) $-1.39\mathrm{dB}$ (D) None of the above.

16. A 5-V dc voltage with $25 - \Omega$ source resistance is applied at $t = 0$ to the input terminal of a $25 - \Omega$ terminated lossless coaxial of $30\mathrm{m}$ length as the figure below. The initial condition of voltage and current of the cable are $0\mathrm{V}$ and $0\mathrm{A}$. The dielectric constant $(\varepsilon_{\mathrm{r}})$ of the insulating material in the cable is 4, and the characteristic impedance of the cable $(Z_0)$ is $50\Omega$. Please select the closest voltage value at $V_{L}$ at 1s. (A) $5\mathrm{V}$ (B) $2.5\mathrm{V}$ (C) $7.5\mathrm{V}$ (D) None of the above.

115年 - 115 台灣聯合大學系統_碩士班招生考試_電機類：電磁學#139672

114年 - 114 台灣聯合大學系統_碩士班招生考試試題_電機類：電磁學#138442

113年 - 113 台灣聯合大學系統_碩士班招生考試試題_電機類：電磁學#138444

112年 - [無官方正解]112 台灣聯合大學系統_碩士班招生考試試題_電機類：電磁學#138446

111年 - 111 台灣聯合大學系統_碩士班招生考試試題_電機類：電磁學#138448

110年 - [非官方正解]110 國立臺灣大學_碩士班招生考試_電信工程研究所甲組:電磁學及電磁波#113085

110年 - 110 國立臺灣科技大學_碩士班招生試題_電子工程系(丙組)：電磁學#112842

110年 - 110 國立臺灣科技大學_碩士班招生試題_光電工程系：電磁學#111696

110年 - 110 國立臺北科技大學_碩士班招生考試_光電工程系碩士班：電磁學#108271

110年 - [非官方正解]110台灣聯合大學系統_碩士班招生考試_電機類:電磁學#105808