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Resistance depending on temperature please help

  • #1

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 hw says its incorrect
 

Answers and Replies

  • #2
gneill
Mentor
20,793
2,773
Hmm. The numbers look okay to me. Did you include the units when you answered?
 
  • #3
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
 
  • #4
gneill
Mentor
20,793
2,773
How many significant figures do each of the provided numbers have?
 
  • #5
To has 3
Ro has 4
R has 3
alpha has 4
 
  • #6
gneill
Mentor
20,793
2,773
Check http://www.usca.edu/chemistry/genchem/sigfig.htm" [Broken].
 
Last edited by a moderator:
  • #7
ok i put in -34.22 but, it is still wrong
 
  • #8
gneill
Mentor
20,793
2,773
-34.22 has four significant figures. The temperature coefficient has fewer.
 
  • #9
1,137
0
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
gneill
Mentor
20,793
2,773
The provided temperature coefficient for gold has two significant figures. Did you try your result with two significant figures?
 

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