Concept:
Arc welding uses an electric arc to produce heat for melting and joining metals.
Step 1: In arc welding, high heat is produced between the electrode and workpiece.
Step 2: Voltage is required to strike and maintain the arc.
Step 3: According to the given options and answer key, arc welding is carried out with:
\[
80-100\,V
\]
Step 4: This voltage helps establish the arc needed for welding.
\[
\boxed{80-100\,V}
\]