How to find currents and voltages in circuits

  • Thread starter Thread starter chase222
  • Start date Start date
  • Tags Tags
    Circuits Currents
AI Thread Summary
To find the equivalent resistance and currents in the described circuit, first calculate the equivalent resistance of resistors R2 and R3, which are in parallel. The formula for two resistors in parallel is 1/R_eq = 1/R2 + 1/R3, resulting in R_eq = 30 ohms. This equivalent resistor is then in series with R1, giving a total resistance of R_total = R1 + R_eq = 70 ohms. To find the current, use Ohm's Law (I = V/R), applying the total voltage of 120 V across the total resistance. Finally, to find the voltages across each resistor, apply the principles of series and parallel circuits accordingly.
chase222
Messages
12
Reaction score
1
I have to find the Requivalent and all of the currents and voltages in the circuit below.

l------------Resistor 1----l---------l
l l l
battery l l
l Resistor 2 Resistor 3
l l l
l l l
-----------------------------------l

My picture is not showing up right, so I'll try to describe it. The battery is on the left and the wire moves up to the right where resistor 1 is. The wire continues, but splits into two paths (making a parallel). The wire turns to the right, where resistor 2 is, but if you keep going straight and then turn right, that's where resistor 3 is.

they give us the following:
R1=40 ohms
R2=60 ohms
R3=60 ohms
Vtotal=120 V

I am not sure where to even start. I know V=IR, and I-V/R, but I don't know how to find the other numbers. I also know that in a series, current stays the same while voltage changes, while in parallel, current changes, while voltage stays the same.

I also know that for series, the Req= R1+R2, while in a parallel, 1/Req=1/R1+1/R2

I just can't figure out the numbers when you have a parallel in a series. Can you help me get started?
 
Last edited:
Physics news on Phys.org
The two resistors that are in parallel are equivilent to a resisitor with the resistance of R where (1/R)= (1/60)+(1/60) which would be 30 ohms and then that equivilent resistor is in series with the first resistor so don't you just add them together so the total resistance would be 70 ohms?
 
I agree with Yapper .. By your description, it sounds like R2 & R3 are in parallel, so 60ohm || 60ohm = 30 ohms. The 30ohms is then in series with R1. So Req = R1 + R2 || R3

Do you know how to determine all the currents and voltages in your circuit, from here?
 
No, I don't. Could you explain it to me?
 
Could you creat a drawing in paint, so the image would be easier to work with? That way, you might receive more help.
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...

Similar threads

Replies
3
Views
1K
Replies
10
Views
440
Replies
1
Views
697
Replies
13
Views
2K
Replies
18
Views
2K
Replies
21
Views
1K
Replies
3
Views
727
Back
Top