According to P=IV, if P is constant with increase in I (current,) then voltage has to decrease and vice a versa – which means they become inversely proportional but according to Ohm's law they are directly proportional. What role does resistance play?
According to Ohm's law V~I.
But R should also be directly proportional to current as with increase in current heat increases and with heat increase resistance increase. As H=I^2RT
therefore, with increase in current the resistance increases but due to resistance increase current will decrease and therefore resistance shall also decrease.
Please clear the confusion between relation of formulas.
Best Answer
Answering about Ohms law:
from: https://en.wikipedia.org/wiki/Ohm%27s_law#Temperature_effects
You are right about the change in resistivity due to change in the temperature. The resistivity has a dependency on temperature. Ohm's law hence is primary defined in a given state. At a constant applied voltage, the current would decrease as in case of conductors and the current would increase as in case of semiconductors. Ohm's law is applicable in a given state. hence, the variable temperature will not be considered.
https://www.askiitians.com/iit-jee-electric-current/temperature-dependence-of-resistivity/