766_Physics ProblemsTechnical Physics

766_Physics ProblemsTechnical Physics - 106 Current and...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
106 Current and Resistance Q27.8 The bottom of the rods on the Jacob’s Ladder are close enough so that the supplied voltage is sufficient to produce dielectric breakdown of the air. The initial spark at the bottom includes a tube of ionized air molecules. Since this tube containing ions is warmer than the air around it, it is buoyed up by the surrounding air and begins to rise. The ions themselves significantly decrease the resistivity of the air. They significantly lower the dielectric strength of the air, marking longer sparks possible. Internal resistance in the power supply will typically make its terminal voltage drop, so that it cannot produce a spark across the bottom ends of the rods. A single “continuous” spark, therefore will rise up, becoming longer and longer, until the potential difference is not large enough to sustain dielectric breakdown of the air. Once the initial spark stops, another one will form at the bottom, where again, the supplied potential difference is sufficient to break down the air. Q27.9
Background image of page 1
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Ask a homework question - tutors are online