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