Physics about electric circuits: Changing the resistors changes the currents

In summary, the behavior of electric circuits is significantly influenced by the resistors used within them. Altering the resistance alters the flow of electric current, as described by Ohm's Law, which states that current is inversely proportional to resistance. This principle highlights the importance of resistor values in determining circuit performance and functionality.
  • #1
blesssid
2
0
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.
 
Physics news on Phys.org
  • #2
: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
##\ ##
 
Last edited:
  • Like
Likes blesssid
  • #3
Many thanks
 
  • #4
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?
 

FAQ: Physics about electric circuits: Changing the resistors changes the currents

1. How does changing the resistance in a circuit affect the current flow?

According to Ohm's Law, the current (I) flowing through a circuit is inversely proportional to the resistance (R) when the voltage (V) is constant. This means that if you increase the resistance, the current decreases, and if you decrease the resistance, the current increases. The relationship can be expressed with the formula I = V/R.

2. What happens to the total current in a series circuit when one resistor is changed?

In a series circuit, the total current is the same through all components. If you change one resistor, it affects the total resistance of the circuit. Increasing the resistance of one resistor will increase the total resistance, thereby decreasing the total current. Conversely, decreasing that resistor's resistance will lower the total resistance and increase the total current.

3. How does changing resistors in a parallel circuit affect the overall current?

In a parallel circuit, the total current is the sum of the currents through each parallel branch. Changing the resistance of one branch affects the current through that branch according to Ohm's Law. If a resistor is decreased in value, the current through that branch will increase, which can lead to an increase in the total current drawn from the source, depending on the other branches' resistances.

4. Can changing resistors in a circuit cause damage to components?

Yes, changing resistors can potentially cause damage to components if the new resistance values lead to excessive current flow. If the current exceeds the rated limits of components like capacitors, transistors, or integrated circuits, it can lead to overheating, failure, or permanent damage. It is important to ensure that all components are rated for the expected current levels in the circuit.

5. What role does the power rating of a resistor play when changing resistors in a circuit?

The power rating of a resistor indicates the maximum amount of power it can safely dissipate without overheating. When changing resistors, it is crucial to choose resistors with appropriate power ratings to avoid failure. If the power dissipated (calculated as P = I²R or P = V²/R) exceeds the resistor's rating, it can lead to burning out the resistor or causing circuit failure.

Back
Top