In this lecture, Professor Walter Lewin explains the principles behind high-voltage breakdown phenomena such as lightning, sparks, and St. Elmo's fire. He demonstrates how charge distribution on conductors is affected by curvature, leading to higher surface charge density and stronger electric fields at sharper points. The lecture covers the mechanism of electric breakdown, the conditions required for sparks, and the detailed process of lightning strikes, including step leaders and return strokes. It also touches upon related phenomena like corona discharge, St. Elmo's fire, and the historical context of lightning rods.
What phenomenon occurs when the electric field in the air becomes too strong, leading to a discharge? a) Electric current b) Electric breakdown c) Electric potential d) Electric flux
According to the lecture, where is the surface charge density highest on a non-spherical conductor? a) On flat surfaces b) On surfaces with the largest radius of curvature c) On surfaces with the smallest radius of curvature (sharpest points) d) It is uniformly distributed on all surfaces
What is the approximate electric field strength required for breakdown in dry air at one atmosphere? a) 300 V/m b) 3,000 V/m c) 3 million V/m d) 3 billion V/m
Which part of a lightning strike is responsible for most of the light and heat? a) The step leader b) The initial charge buildup in the cloud c) The return stroke d) The corona discharge
What did Benjamin Franklin propose as a way to protect buildings from lightning? a) Using large, blunt conductors b) Installing a continuous corona discharge using sharp points (lightning rods) c) Grounding the building with a very thick wire d) Evacuating the building during thunderstorms
Turn this video into a tweet...
