A) independent of temperature
B) increases as the temperature rises
C) decreases as the temperature rises
D) increases or decreases as temperature rises depending upon the metal
Correct Answer: B
Solution :
(b) increases as the temperature rises The resistance of a metallic wire at temperature \[t{}^\circ C\] is given by \[{{R}_{t}}={{R}_{0}}(1+\alpha t)\] where, \[\alpha \] is the temperature coefficient of resistance and \[{{R}_{0}}\] is the resistance of a wire at \[0{}^\circ C\]. For metals, \[\alpha \] is positive. Hence, resistance of a wire increases with increase in temperature. Also, from Ohm's law \[\frac{V}{l}=R\] Hence, on increasing the temperature, the ratio \[\frac{V}{l}\]increases.
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