How to find currents and voltages in circuits

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SUMMARY

The discussion focuses on calculating the equivalent resistance, currents, and voltages in a circuit containing resistors in series and parallel configurations. The circuit includes a battery with a total voltage of 120 V, Resistor 1 (R1) at 40 ohms, and two parallel resistors, Resistor 2 (R2) and Resistor 3 (R3), each at 60 ohms. The equivalent resistance for R2 and R3 is calculated as 30 ohms, which is then added to R1 to yield a total equivalent resistance (Req) of 70 ohms. The participants emphasize the application of Ohm's Law (V=IR) and the rules for series and parallel circuits to find the currents and voltages.

PREREQUISITES
  • Understanding of Ohm's Law (V=IR)
  • Knowledge of series and parallel resistor configurations
  • Ability to calculate equivalent resistance (Req) for series and parallel circuits
  • Familiarity with basic circuit analysis techniques
NEXT STEPS
  • Learn how to calculate total current using Ohm's Law in complex circuits
  • Study Kirchhoff's Voltage and Current Laws for circuit analysis
  • Explore advanced circuit simulation tools like LTspice or Multisim
  • Investigate the impact of varying resistor values on circuit performance
USEFUL FOR

Electrical engineering students, hobbyists building circuits, and anyone involved in circuit design and analysis will benefit from this discussion.

chase222
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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?
 
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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.
 
The book claims the answer is that all the magnitudes are the same because "the gravitational force on the penguin is the same". I'm having trouble understanding this. I thought the buoyant force was equal to the weight of the fluid displaced. Weight depends on mass which depends on density. Therefore, due to the differing densities the buoyant force will be different in each case? Is this incorrect?

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