Physics about electric circuits: Changing the resistors changes the currents

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SUMMARY

This discussion focuses on the impact of changing resistors on current in electric circuits, emphasizing the application of Kirchhoff's Laws and Ohm's Law. Participants recommend redrawing the circuit for clarity and suggest using specific variables for resistors and currents, such as ##r_1, r_2, I_1, I_2, I_3, I_4##. The conversation highlights the necessity of formulating a comprehensive set of equations to solve the circuit problem, particularly noting the importance of Kirchhoff's Loop and Junction Rules alongside Ohm's Law.

PREREQUISITES
  • Understanding of Ohm's Law (I = U/R)
  • Familiarity with Kirchhoff's Loop Rule
  • Knowledge of Kirchhoff's Junction Rule
  • Basic circuit diagram drawing skills
NEXT STEPS
  • Study Kirchhoff's Laws in detail to apply them effectively in circuit analysis
  • Practice redrawing complex circuits for better visualization
  • Learn how to set up and solve systems of equations for multiple variables in circuit problems
  • Explore advanced circuit analysis techniques, such as nodal and mesh analysis
USEFUL FOR

Students studying electrical engineering, physics enthusiasts, and anyone looking to deepen their understanding of electric circuits and current behavior.

blesssid
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New user has been reminded to always show their work on schoolwork problems.
Homework Statement
In an experiment with the circuit diagram as shown. Power source U = 1V; resistance R = 1Ω; Ammeters A1 and A2 are ideal ammeters (with zero resistance), and the currents through them can change when we change the value of the resistor r. Adjusting the value of the resistor r so that ammeter A2 shows 1A, ammeter A1 shows 3.5A. If we change the position between R1 and R2 and adjust the resistor r the A2 shows 1A, then A1 shows 7/3A .Calculate R1 and R2.
Relevant Equations
I = U/R
z5394064647850_0a06a36d985b29283c93c8b30763fd44.jpg

Please help me with this homework! I haven't had any solutions since it is all unclear.
 
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:welcome:

Unfortunately the PF rules do require you to post your best effort.
The least you can do is redraw the circuit so it looks more like something you can recognize and calculate...

[edit] to help you on your way: You have 2 situations, so you want to make a list of variables you are going to use to build a set of equations: e.g. two (unknown) values for ##r## means you need an ##r_1## and an ##r_2##. Four (known) currents means four variables like ##I_1, I_2, I_3, I_4##.

Your list of equations needs more than just Ohm with so many variables (think Kirchoff)

[edit] more help: with redrawing the circuit I mean something that has the battery on the left :rolleyes:

1714386180315.png
##\ ##
 
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Many thanks
 
blesssid said:
Relevant Equations: I = U/R
You will also need the equations of Kirchhoff's Loop Rule and Kirchhoff's Junction Rule.
Also, in the problem statement you have ##R=10##. I assume that's a typo and should be ##R=10\ \Omega##.

Have you covered Kirchhoff's Laws in your course?
 

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