Current Electricity Charging Discharging Of Capacitors Question 688
Question: At what temperature will the resistance of a copper wire becomes three times its value at $ 0{}^\circ C $ ? (Temperature coefficient of resistance of copper is $ 4\times {{10}^{-3}}/{}^\circ C $ )
Options:
A) $ 550{}^\circ C $
B) $ 500{}^\circ C $
C) $ 450{}^\circ C $
D) $ 400{}^\circ C $
Show Answer
Answer:
Correct Answer: B
Solution:
[b] $ R _{t}=R _{0}( 1+\alpha t ) $ at $ t{}^\circ C $
$ R _{t}=3R _{0} $
$ \alpha =4\times {{10}^{-3}}/{}^\circ C $
$ 3R _{0}=R _{0}( 1+4\times {{10}^{-3}}\times t ) $
$ \
Therefore ,,,,,,3-1=4\times {{10}^{-3}}\times t $
$ \
Therefore ,,,,t=\frac{2}{4\times {{10}^{-3}}}=500{}^\circ C $
BETA
