Voltage-resistance graph for this circuit with a variable resistance

AI Thread Summary
The discussion revolves around a voltage-resistance graph for a circuit with variable resistance. The user plotted the graph and found discrepancies in voltage readings at 600 ohms, where expected values were not met. Questions arose regarding the linearity of the graph and the accuracy of calculations, prompting a request for clarification on the potential divider equation. The teacher confirmed that the equation provided is correct and indicated that the relationship resembles a 1/x curve. The conversation emphasizes the importance of showing calculations for better understanding and troubleshooting.
shirozack
Messages
37
Reaction score
3
Homework Statement
a 600 ohm fixed resistor Rf is connected in series with a variable resistor Rv that goes from 0-800ohms. the battery is 6V.

when Rv is 0ohm, the voltage Vf across the Rf is 6V. Vv is 0V.

when Rv is 800 ohm, Vf is 2.6V and Vv is 3.4V

Plot the v-r graph of both Vf and Vv (from 0 to 6V) against Rv (from 0-800 ohms)
Relevant Equations
na
I have plotted the V-R graph.

when Rv is 600 ohms, Rf is also 600ohms, which means the voltage across both resistors should be split evenly at 3V each since batt is 6V.

however, from the graph, i noticed that Vf is 3.4V and Vv is 2.6V instead at 600 ohms.

i would like to know where did it go wrong? are the graphs not supposed to be a straight line?

why is the intersection at 700 ohms instead which is 3V.

thanks
 

Attachments

  • 1.jpg
    1.jpg
    13.8 KB · Views: 57
Physics news on Phys.org
shirozack said:
are the graphs not supposed to be a straight line?
Why should they be? Can you write the equation?
 
haruspex said:
Why should they be? Can you write the equation?
this was the answer given by the teacher. is it wrong?

the potential dividing equation?

Vfixed = Vbatt x [ 600 / (600+Rvariable) ] ?

so it's like a 1/x curve?
 
shirozack said:
this was the answer given by the teacher. is it wrong?

the potential dividing equation?

Vfixed = Vbatt x [ 600 / (600+Rvariable) ] ?

so it's like a 1/x curve?
Yes, similar to that.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
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...
Back
Top