How is the loop law applicable when I connect a battery with an ideal copper wire? We would have a potential rise but where is potential drop? Considering wire to be having negligible resistance.
 A: There would be a potential drop. If the wire has literally $0$ resistance, then this is a nonphysical question and no physical answer can be provided. 
Energy will be lost due to heat in the wire. The current will will be very high, as $I=\frac{V}{R}$ and $R$ is very low, and the power dissipated (heat) will be very high, as $P=IV$.
A: A power source usually has internal resistance; if you short the terminals of your battery with a perfect conductor the internal resistance will limit the current (and the voltage drop across the internal resistance will equal the potential rise of the battery).
If you have a power source with zero nominal internal impedance (you can get really close with a good voltage regulator) the electronics behind this would still have a finite power - so when you short the terminals, the total amount of current that can flow will be limited by the construction of the power source.
And if you have a limitless power source, there are governments that will want to talk to you.
