HW 1 material

Question 1

Potential at A is 0V, what is the potential at B? (What are the steps)

Answer 1

Find V_t = 20V - 4V = 16V
Find R_t = 1k + 2k + 5k = 8k
Find I = V_t/R_t
Use loop rule: +20V - IR_1 - 4V

Question 2

Using only equivalent resistance methods, how would you find the voltage between A and B

Answer 2

Simplify the circuit from right to left to find the voltage across the 8k, then use that as the input (no longer using 10V, 2k, and 8k) and repeat until you get V_AB

Question 3

How would you find the voltage of each resistor assuming they are all equivalent

Answer 3

1) Simplify from right to left to find total current
2) VR1=I*R1
3) VR2=Vs-VR1
4) Use VR2 as input and find VR3 and VR4. Since R2 (R) is in parallel with R34 (2R), then voltage stays constant
5) VR3=VR4=(1/2)VR2

Question 4

What does a voltage divider look like?

Answer 4

Question 5

For a voltage divider, what is Vout in terms of Vs, R1, and R2?

Answer 5

Question 6

What is Vth?

Answer 6

Vth = Vout or the voltage across the load

Question 7

What is Rth?

Answer 7

Question 8

For a voltage divider, how to find R1 and R2 assuming you know RL, Vs, and Vout?

Answer 8

1) Use the equation for Vout and find the ratio of R2 to R1
2) After finding Vth, replace R2 with the ratio to R1 in the Rth equation to find the ratio of Rth to R1
3) Replace R1 with RL and R2 with Rth in the Vout equation, sub in the ratio of Rth to R1, solve for R1
4) Use the ratio of R2 to R1 to find R2

Question 9

What are the steps for Kirchoff’s rule?

Answer 9

1) Find junction equation
2) Find TWO loops and set them equal to 0
3) Use junction equation to sub currents in two loop equations
4) Subtract 1’ from 2’ (multiply one or the other by some number if necessary) to cancel some terms
5) Use known values to find remaining current in 2’
6) Sub that into 1’ to find that current
7) Use junction equation to find final current