Using multiple contacts and rapid opening times helps ______ the arc by reducing the cross sectional area of the arc or by lengthening it.

Using multiple contacts and rapid opening times helps ______ the arc by reducing the cross sectional area of the arc or by lengthening it.

• A. Cool
• B. Amplify
• C. Shorten
• D. Sustain

Answer: (A)

Faster opening with multiple contacts helps cool the arc. When the contacts separate quickly and across several points, the arc is forced to spread out and travel a longer path while its cross-sectional area effectively becomes smaller. A longer, thinner arc has higher resistance and lower current density, so more energy is dissipated into the surrounding air and the arc is easier to quench. The other possibilities would either boost the arc’s energy or keep it going, not promote cooling and extinction.

Faster opening with multiple contacts helps cool the arc. When the contacts separate quickly and across several points, the arc is forced to spread out and travel a longer path while its cross-sectional area effectively becomes smaller. A longer, thinner arc has higher resistance and lower current density, so more energy is dissipated into the surrounding air and the arc is easier to quench. The other possibilities would either boost the arc’s energy or keep it going, not promote cooling and extinction.