111-1 Fundamentals of Electronics
Homework 1 (Due 9/29)
10 point for each question, 10 points for each LTSPICE/PSPICE simulation
1. The current entering the terminal of the following figures is i=0 for t<0 and
i=40te-500tA for t≥0
(a) Please find the charge accumulating (or deliver) to the component related to
time.
(b) Find the charge that has accumulated at t=1ms.
2. Two electric circuit, represented by boxes A and B, are connected as shown
follows:
For each of the following sets of values, calculate the power in the
interconnection and state whether the power is flow from A to B or B to A.
(a) I=8A, v=40V
(b) I= -2A, v= -10V
(c) I=2A, v= -50V
(d) I= -10A, v=20V
3. If you are driving a Tesla, unfortunately, the battery is almost dead. You plan to
charge the vehicle by another electric car. How should you connect the battery?
If the charge port has voltage 12V and a current is found to be 40A, how much
energy transferred for 1.5min charging?
4. The numerical values for the currents and voltages in the following circuit are
given below:
(a) Please find the total power transferred from the circuit:
(b) Please realize this circuit by LTSPICE / PSPICE (hints: you can use VDC for
power delivery and R for power dissipation)
5. The circuit shown below has 1A current at 70Ω resistor.
(a) Please find the voltages and currents in each resistor
(b) Verify that the total power dissipated in the circuit equals the power
delivered by the voltage source
(c) Verify your answer by using LTSPICE / PSPICE
6. (a) Find the voltage vx in the following circuit:
(b) If the source is replaced with one with voltage Vs, please find the vx as a
function of Vs
7. Find the value of the unknown resistor Rx in the Wheatstone bridge with an ideal
ammeter. What are the current flows from each resistor? Show that the voltage
is equal on both side of the ammeter. What are the current flows and power
dissipations from each
8. A resistive touch screen has (x-y) 640X1024 pixels resolution. The resistive grid
has 8V applied in both the x- and y-directions. If the touch point is at (480,192),
calculate the voltages Vx and Vy.
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