Output Voltage

  • Thread starter TyErd
  • Start date
  • #1
TyErd
299
0

Homework Statement


The circuit below combines variable resistors R1 and R2 with fixed resistors to make a complex voltage divider.

If the switch is closed and R1=8000ohms and R2 is 5000ohms, what is the output voltage.


Homework Equations


V=IR


The Attempt at a Solution


the equivalent resistor of 1000 and 8000 is 3077 and the current through that is 0.03A. I am not sure what to do after that.
 

Attachments

  • circuit1.JPG
    circuit1.JPG
    6.2 KB · Views: 328

Answers and Replies

  • #2
Integral
Staff Emeritus
Science Advisor
Gold Member
7,253
63
You do not need to know the resistor values. Look at the diagram and think about it.
 
  • #3
TyErd
299
0
um..a current goes through the first parallel part and then splits up when entering the next parallel part...
 
  • #4
TyErd
299
0
not sure whrre to look
 
  • #5
TyErd
299
0
...?
 
  • #6
TyErd
299
0
is it 0 because the current will go through the part of the circuit where there's the least resistance?
 
  • #7
willem2
2,103
365
is it 0 because the current will go through the part of the circuit where there's the least resistance?

Yes. All the current will go through the closed switch and none of it through the two resistances that are parallel with it.
The output voltage is I_switch * R_switch and R_switch = 0.

Although it's not relevant for the answer, the equivalent resistance of 1000 ohm and
8000 ohm resistances in parallel is not 3077 ohm. The equivalent resistance of 2 parallel resistances should be smaller then the smallest of the resistances.
 
  • #8
TyErd
299
0
okay thnx, my mistake the equivalent resistor should be 889ohms. Question, why does the current only go through the switch? Is it because its the easiest path?
 

Suggested for: Output Voltage

  • Last Post
Replies
1
Views
182
  • Last Post
Replies
19
Views
495
Replies
21
Views
320
Replies
2
Views
101
Replies
2
Views
231
  • Last Post
Replies
26
Views
2K
Replies
30
Views
702
Replies
4
Views
471
Replies
1
Views
230
  • Last Post
Replies
3
Views
676
Top