What is $Re\left[\frac{e^{i\omega t}}{1+i}\right]$? 1. $\frac{1}{\sqrt{2}}\cos(\omega t + \pi/4)$ 2. $\frac{1}{\sqrt{2}}\cos(\omega t - \pi/4)$ 3. $\frac{1}2\cos(\omega t + \pi/4)$ 4. $\frac{1}2\cos(\omega t - \pi/4)$ 5. Something else Note: * Correct Answer: B
## Announcements * Quiz 3 (next Friday 2/17) - RLC circuits * Solve a circuit problem using the phasor method * Discuss limits on the response and how it might act as a filter
AC voltage $V$ and current $I$ vs time $t$ are as shown: <img src="./images/IV_graphs.png" align="center" style="width: 600px";/> The graph shows that.. 1. $I$ leads $V$ ( $I$ peaks before $V$ peaks ) 2. $I$ lags $V$ ( $I$ peaks after $V$ peaks ) 3. Neither Note: * Correct Answer: B
Suppose you have a circuit driven by a voltage: $$V(t)=V_0\cos(\omega t)$$ You observe the resulting current is: $$I(t) = I_0\cos(\omega t-\pi/4)$$ Would you say the current is 1. leading 2. lagging the voltage by 45 degrees? Note: * Correct Answer: B
Two LR circuits driven by an AC power supply are shown below. <img src="./images/two_RL_circuits.png" align="center" style="width: 800px";/> Which circuit is a low pass filter? 1. The left circuit 2. The right circuit 3. Both circuits 4. Neither circuit Note: * Correct Answer: B
Two RC circuits driven by an AC power supply are shown below. <img src="./images/two_RC_circuits.png" align="center" style="width: 800px";/> Which circuit is a high pass filter? 1. The left circuit 2. The right circuit 3. Both circuits 4. Neither circuit Note: * Correct Answer: A