$A\,\,{5\,^o}C$ rise in the temperature is observed in a conductor by passing some current. When the current is doubled, then rise in temperature will be equal to ............. $^oC$
A$5$
B$10$
C$20$
D$40$
Medium
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C$20$
c (c) Using conservation of energy
Supplied electric energy = absorbed heat energy
$ \Rightarrow $ ${i^2}Rt = mST$
$ \Rightarrow $ $T \propto {i^2}$ ($T$ - change in temperature)
i.e. when $i$ is doubled $T$ will be four times i.e. $5 \times 4 = {20\,^o}C$
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