A) \[{{0.0012}^{0}}{{C}^{-1}}\]
B) \[{{0.0024}^{0}}{{C}^{-1}}\]
C) \[{{0.0032}^{0}}{{C}^{-1}}\]
D) \[{{0.0064}^{0}}{{C}^{-1}}\]
Correct Answer: D
Solution :
If the resistance of wire at \[0{{\,}^{o}}C\]be \[{{R}_{0}}\]and at \[t{{\,}^{o}}C\] be \[{{R}_{t}},\]then the value of \[{{R}_{t}},\]will be obtains from the following formula \[{{R}_{t}}={{R}_{0}}(1+\alpha \,t)\] where\[\alpha \]is a constant called tempera coefficient of resistance. \[\Rightarrow \] \[\alpha =\frac{{{R}_{t}}-{{R}_{0}}}{{{R}_{0}}t}/{{\,}^{o}}C\] Putting the numerical values, we have \[\alpha =\frac{4.5-3.1}{3.1\times (100-30)}\] \[=\frac{1.4}{3.1\times 70}\] \[=\frac{1.4}{217}=0.0064{{\,}^{o}}{{C}^{-1}}\]
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