A) 80.0096 cm
B) 80.0272 cm
C) 1 cm
D) 25.2 cm
Correct Answer: A
Solution :
With temperature rise (same \[25{}^\circ C\] for both), both steel scale and copper wire expand. Hence length of copper wire w.r.t. steel scale or apparent length of copper wire will increase after rise in temperature \[{{L}_{app}}=L{{'}_{cu}}-L{{'}_{steel}}\] \[=[{{L}_{0}}(1+{{\alpha }_{Cu}}\Delta \theta )-{{L}_{0}}(1+{{\alpha }_{s}}\Delta \theta )]\] \[\Rightarrow \]\[{{L}_{app}}={{L}_{0}}({{\alpha }_{Cu}}-{{\alpha }_{s}})\Delta \theta \] \[=80(17\times {{10}^{-6}}-11\times {{10}^{-6}})\times 20\] = 80.0096 cmYou need to login to perform this action.
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