Answer / sirin dutta chowdhury

This question seems to be wrong.

As temperature increases, resistivity of metals
also increases.These metals are called Ohmic conductors.
The substances, for which conductivity increases with temp
rise dont obey ohm's law and are caller non ohmic
conductors (carbon etc).
The metarials used for transmission lines are all
obviously Ohmic conductors(Cu, Al etc).Hence there is no
question of increse of conductivity of transmission wires
with temp rise.

Adding to it, for this reason, to keep temp rise
within permissible limit,losses of transmission lines are
kept within limit by raising voltage level & reducing
current level through it.

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