How to Calculate the Resistance of Nichrome in a Series Circuit with Graphite?

  • Thread starter Thread starter Ugnius
  • Start date Start date
  • Tags Tags
    Resistance Wire
Click For Summary

Homework Help Overview

The discussion revolves around calculating the resistance of nichrome in a series circuit that includes graphite, with a total resistance of 5.8 ohms. The problem involves understanding how temperature coefficients affect resistance and the implications of combining materials with different thermal properties.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants are exploring the implications of the temperature coefficients of resistance for graphite and nichrome. There are questions about the adequacy of the provided information and whether the stated resistance is sufficient to derive the resistance of nichrome. Some participants are attempting to clarify the relationship between the resistances of the two materials.

Discussion Status

The discussion is active, with participants raising questions about the completeness of the problem statement and the assumptions regarding temperature independence. Some guidance has been offered regarding the formulation of equations based on the resistances of the materials involved.

Contextual Notes

Participants note that the problem does not provide specific temperature values, which may affect the approach to finding the solution. There is also mention of the resistance of the combined materials being independent of temperature, which is a critical aspect of the discussion.

Ugnius
Messages
54
Reaction score
10
Homework Statement
Two wires are connected in series. One made of coal , other one of nichrome. Series resistance is 5.8 ohms , what is the resistance of nichrome wire? Temperature coef. of resistance of coal -0.0005K^-1 , 0.0004K^-1 of nichrome
Relevant Equations
.
I don't really have any equations or idea how to solve this. I searched for relevant equations and only R=Rref(1+α(T-Tref)) pops up. I wasn't given any temperatures so I guess there must be some other way to solve this. Maybe anyone has idea how to approach this?
 
Physics news on Phys.org
Also it's mentioned that this compounds resistance isn't affected by temperature. so maybe that would make difference
 
Ugnius said:
Also it's mentioned that this compounds resistance isn't affected by temperature. so maybe that would make difference
Yes, that's critical. It let's you find the ratio of the two lengths. But there still doesn't seem to be quite enough info. Are you sure you have stated it completely?
(Coal?)

Edit: it let's you find the ratio of the resistances, not the ratio of the lengths, so it is enough information.
 
Last edited:
1634758454673.png

So this is the statement in my native language, i will translate it word by word.
E27. In order to get a conductor , with resistance independent from temperature , we combine coal and nichrome wires in series. If that stated combination has a resistance of 5.8 ohm , what is resistance of nichrome? αcoal=-0.0005K-1 , αnichrome=0.0004K-1. Thats it.
 
Ugnius said:
View attachment 290949
So this is the statement in my native language, i will translate it word by word.
E27. In order to get a conductor , with resistance independent from temperature , we combine coal and nichrome wires in series. If that stated combination has a resistance of 5.8 ohm , what is resistance of nichrome? αcoal=-0.0005K-1 , αnichrome=0.0004K-1. Thats it.
Maybe the question is this:

A graphite wire and a nichrome wire are connected in series. Their total resistance is 5.8Ω and is independent of temperature.

For some reference temperature [probably 20ºC but it doesn’t matter] the temperature coefficients of resistance of graphite and nichrome are -0.0005K⁻¹ and 0.0004K⁻¹ respectively.

What is the resistance of the nichrome wire at the reference temperature?
_________

Hint: Call the resistances of the graphite and nichrome wires at the reference temperature ##R_G## and ##R_N##. Can you write down any equations, based on the information in the question, using ##R_G## and ##R_N##?
 

Similar threads

  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 5 ·
Replies
5
Views
1K
  • · Replies 3 ·
Replies
3
Views
3K
  • · Replies 4 ·
Replies
4
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 10 ·
Replies
10
Views
2K
  • · Replies 20 ·
Replies
20
Views
6K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 21 ·
Replies
21
Views
11K