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Current Electricity

Question
CBSEENPH12037469

A silver wire has a resistance of 2.1 Ω at 27.5 °C, and a resistance of 2.7 Ω at 100 °C. Determine the temperature co-efficient of resistivity of silver.

Solution

Given,
Resitance of silver wire, R1 = 2.1 Ω
Room temperature, t27.5 °C
Resistance of wire at temperature 100o C, R2= 2.7  Ω 
Using the relation,

 R2=R1[1+α(t2-t1)] 

where, t2 = 100° C 

Therefore, temperature coefficient of resistivity of silver is given by, 

α = R2-R1R1(t2-t1)     = 2.7-2.12.1(100-27.5)
  =0.62.1 × 72.5= 0.6152.25 = 0.0039 °C-1