When the wire is bent in the form of a square and connected between \(M\) and \(N\) as shown in fig.\((2)\), the effective resistance between \(M\) and \(N\) decreases to one fourth of the value in fig.\((1)\). The current increases four times the initial value according to the relation \(V=I R\). Since \(H=I^2 R t\), the decrease in the value of resistance is more than compensated by the increases in the value of current. Hence heat produced increases. Percentage loss in energy during the collision \(\simeq 56 \%\)