# Embedded Systems: Homework 1

This homework assignment is **due Tuesday, October 14th**
at the beginning
of class. You may hand in a hard copy in class or an electronic copy
prior to coming to class. All work that you hand in must be your own.
Please make sure that your assignment is well-formatted (so that it is
understandable), and please show your work.

## Question 1

Consider the following circuit:

Assume that R = 100 ohms and that the voltage drop across each LED is
2 Volts.

- What is the current flow through the resistor?
- How much work does each LED perform?
- How does the work manifest itself?

## Question 2

Consider the following circuit:

Assume that R1 = R5 = 10 ohms, R2 = R3 = 25 ohms, and R4 = 100 ohms.

- What is the voltage at point A?
- At point B?
- What is the effective resistance of this lattice?
- What is the current flow through R5?
- How much work is done by R1?
- How does this work manifest itself?

## Question 3

Consider the following circuit:

- With the button in the state as shown, what is the voltage at
point A?
- What is the current across R1, R2 and C (assume steady state)?

- With the button pressed and with the circuit in steady state,
what is the voltage at point A?
- What is the current across R1, R2, and C?

- Assume that the circuit is in steady state with the button in
the state as shown and that at time t=0, the button is
pressed. What is the temporal evolution of the voltage at
point A?
- What is the time constant of this evolution?
- What is the flow of current (as a function of time) across R1,
R2, and C?

- Assume that the circuit is in steady state with the button
pressed and that at time t=0, the button is released. What is
the temporal evolution of the voltage at point A?
- What is the time constant?

## Question 4

How much time did you spend on this assignment?

*fagg@cs.umass.edu*

Last modified: Sun Sep 28 23:31:16 2003