Physics about electric circuits: Changing the resistors changes the currents

AI Thread Summary
To solve the homework problem on electric circuits, it's essential to redraw the circuit for clarity and to identify the variables involved, such as resistors and currents. Two situations require defining unknown values for resistors and known values for currents to create a set of equations. The equations should incorporate both Ohm's Law and Kirchhoff's Laws, including the Loop and Junction Rules, to analyze the circuit accurately. It's noted that a potential typo in the problem statement regarding resistance should be corrected to R=10 Ω. Understanding Kirchhoff's Laws is crucial for tackling this type of circuit analysis.
blesssid
Messages
2
Reaction score
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
: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:
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?
 
Thread 'Minimum mass of a block'
Here we know that if block B is going to move up or just be at the verge of moving up ##Mg \sin \theta ## will act downwards and maximum static friction will act downwards ## \mu Mg \cos \theta ## Now what im confused by is how will we know " how quickly" block B reaches its maximum static friction value without any numbers, the suggested solution says that when block A is at its maximum extension, then block B will start to move up but with a certain set of values couldn't block A reach...
TL;DR Summary: Find Electric field due to charges between 2 parallel infinite planes using Gauss law at any point Here's the diagram. We have a uniform p (rho) density of charges between 2 infinite planes in the cartesian coordinates system. I used a cube of thickness a that spans from z=-a/2 to z=a/2 as a Gaussian surface, each side of the cube has area A. I know that the field depends only on z since there is translational invariance in x and y directions because the planes are...
Thread 'Calculation of Tensile Forces in Piston-Type Water-Lifting Devices at Elevated Locations'
Figure 1 Overall Structure Diagram Figure 2: Top view of the piston when it is cylindrical A circular opening is created at a height of 5 meters above the water surface. Inside this opening is a sleeve-type piston with a cross-sectional area of 1 square meter. The piston is pulled to the right at a constant speed. The pulling force is(Figure 2): F = ρshg = 1000 × 1 × 5 × 10 = 50,000 N. Figure 3: Modifying the structure to incorporate a fixed internal piston When I modify the piston...
Back
Top