Resistance depending on temperature

AI Thread Summary
The discussion revolves around calculating the temperature of a liquid bath based on the resistance change of a gold wire. The initial resistance at 30.3°C is 124.9 ohms, which decreases to 97.5 ohms in the bath. The temperature coefficient for gold is given as 0.0034 (C)−1 at 20°C, and the formula used is R = Ro[1 + alpha(t - to)]. Participants are troubleshooting an incorrect answer of -34.2°C, considering significant figures and the accuracy of their calculations. The conversation emphasizes the importance of matching significant figures with the provided data to achieve the correct temperature result.
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Homework Statement



At 30.3C, the resistance of a segment of gold
wire is 124.9 omega When the wire is placed in a
liquid bath, the resistance decreases to 97.5 omega
What is the temperature of the bath?
The temperature coefficient for gold is
0.0034 (C)−1 at 20C.
Answer in units of C.


Homework Equations



used R=Ro[1+alpha(t-to)

The Attempt at a Solution



I got -34.2, but the homework says its incorrect
 
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Hmm. The numbers look okay to me. Did you include the units when you answered?
 
gneill said:
Hmm. The numbers look okay to me. Did you include the units when you answered?

yes do you think it could be wrong because of sigfigs so it be -34.22
 
How many significant figures do each of the provided numbers have?
 
To has 3
Ro has 4
R has 3
alpha has 4
 
Check http://www.usca.edu/chemistry/genchem/sigfig.htm" .
 
Last edited by a moderator:
ok i put in -34.22 but, it is still wrong
 
-34.22 has four significant figures. The temperature coefficient has fewer.
 
I'm getting something else ... its less than your answer

why not use the temp you got and find the resistance and match it with 124.9 ohm
 
  • #10
I don't really understand what you are trying to say
 
  • #11
The provided temperature coefficient for gold has two significant figures. Did you try your result with two significant figures?
 

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