Our global statement of energy conservation is: $$\dfrac{dU_q}{dt} + \dfrac{dU_e}{dt} = -\iint \mathbf{S}\cdot d\mathbf{A}$$ Which term describes that energy of the electromagnetic field? 1. $\frac{dU_q}{dt}$ 2. $\frac{dU_e}{dt}$ 3. $-\iint \mathbf{S}\cdot d\mathbf{A}$ 4. ??? Note: * Correct Answer: B
Our global statement of energy conservation is: $$\dfrac{dU_q}{dt} + \dfrac{dU_e}{dt} = -\iint \mathbf{S}\cdot d\mathbf{A}$$ What does the integral term (without the minus sign) refer to? 2. Total energy coming in 3. Total energy going out 3. Rate of total energy coming in 4. Rate of total energy going out Note: * Correct Answer: D
Consider a current $I$ flowing through a cylindrical resistor of length $L$ and radius $a$ with voltage $V$ applied. What is the E field inside the resistor? <img src="./images/cylindrical_resistor.png" align="center" style="width: 400px";/> 1. $(V/L) \hat{z}$ 2. $(V/L) \hat{\phi}$ 3. $(V/L) \hat{s}$ 4. $(Vs/L^2) \hat{z}$ 5. None of the above Note: * Correct Answer: A
Consider a current $I$ flowing through a cylindrical resistor of length $L$ and radius $a$ with voltage $V$ applied. What is the B field inside the resistor? <img src="./images/cylindrical_resistor.png" align="center" style="width: 400px";/> 1. $(I\mu_0/2\pi s) \hat{\phi}$ 2. $(I\mu_0s/2\pi a^2) \hat{\phi}$ 3. $(I\mu_0/2\pi a) \hat{\phi}$ 4. $-(I\mu_0/2\pi a) \hat{\phi}$ 5. None of the above Note: * Correct Answer: B
Consider a current $I$ flowing through a cylindrical resistor of length $L$ and radius $a$ with voltage $V$ applied. What is the direction of the $\mathbf{S}$ vector on the outer curved surface of the resistor? <img src="./images/cylindrical_resistor.png" align="center" style="width: 400px";/> 1. $\pm \hat{\phi}$ 2. $\pm \hat{s}$ 3. $\pm \hat{z}$ 4. ??? Note: * Correct Answer: B