What is a common consequence of arcing at contact points in a DC circuit?

Arcing at contact points in a DC circuit typically generates a significant amount of heat. This occurs because the electrical current jumps across a gap in the circuit, which creates a high-temperature plasma. This intense heat can result in various problems, including damaging the contact surfaces and causing wear over time. The heat generated can lead to the melting of materials, degradation of the components involved, and even potential failure of electrical connections.

In contrast, options like improved conductivity and reduced resistance are unlikely to be outcomes of arcing, as arcing tends to create instability in the circuit. Mechanical failure may occur as a result of the heat generated, but the immediate and most characteristic consequence is the generation of heat itself. Therefore, heat generation is rightly identified as the common consequence of arcing at contact points in a DC circuit.