Suppose there is a ideal voltage source which can provide infinite power if that is needed in an ideal scenario. Now suppose a resister R is connected across it and the e.m.f is E. So by ohm's law the entire E will fall across R, despite of whatever the value of R is; except for 2 conditions,
If R=0, I=E/0=infinity. So E=IR=infinity*0=0, But if the supply gives E volts out and if the charges dissipates it's Total energy by end of the 0 ohm resistance and with the help of infinite current, then how the voltage across it can be 0 and not E?
If R=infinite, I=E/infinite=0. So, E=IR=0*infinite=0. Again the same thing. How can E be zero when at first E was not zero when supplied?
I know in real world nothing is ideal but here I'm taking an ideal case for calculations. And I also know in case 2 if R=infinite or opened the voltage across it will be E but why the equation is not supporting that? And I'm not sure what will be the voltage in case 1. Is there any asymptote in the E vs R graph which is causing those behaviour in two cases?