What is the breakdown threshold in air?

What is the breakdown threshold in air?

• A. 3 Kilovolts
• B. 0.3 Megavolts
• C. 3 Megavolts
• D. 3 Volts

Answer: (C)

Air can act as an insulator only up to a certain electric field strength. The breakdown threshold is the field strength at which air molecules become ionized and a conductive path forms, producing a spark. In air, this threshold is about 3 million volts per meter (roughly 3 MV/m). So, if the gap is about one meter, you’d expect breakdown around 3 million volts; for smaller gaps, the required voltage scales with the distance. The other options are far too small to overcome air’s insulating properties. The important point is that breakdown is dictated by the electric field, not just the total voltage.

Air can act as an insulator only up to a certain electric field strength. The breakdown threshold is the field strength at which air molecules become ionized and a conductive path forms, producing a spark. In air, this threshold is about 3 million volts per meter (roughly 3 MV/m). So, if the gap is about one meter, you’d expect breakdown around 3 million volts; for smaller gaps, the required voltage scales with the distance. The other options are far too small to overcome air’s insulating properties. The important point is that breakdown is dictated by the electric field, not just the total voltage.