﻿[Script Info] Title: [Events] Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text Dialogue: 0,0:00:00.00,0:00:02.00,Default,,0000,0000,0000,,Well, we've already learned a lot about electricity. Dialogue: 0,0:00:02.00,0:00:05.00,Default,,0000,0000,0000,,We know that negative charges like to be with positive charges. Dialogue: 0,0:00:05.00,0:00:08.00,Default,,0000,0000,0000,,We know four methods to charge an object, Dialogue: 0,0:00:08.00,0:00:12.00,Default,,0000,0000,0000,,and we've learned that the earth is both a source and a sink for electrons. Dialogue: 0,0:00:12.00,0:00:14.00,Default,,0000,0000,0000,,But one thing we haven't talked about at all— Dialogue: 0,0:00:14.00,0:00:17.00,Default,,0000,0000,0000,,one of the most important concepts in physics is energy. Dialogue: 0,0:00:17.00,0:00:20.00,Default,,0000,0000,0000,,Why don't we go back to Professor Fregonese and see what he has to say Dialogue: 0,0:00:20.00,0:00:22.00,Default,,0000,0000,0000,,about energy as it relates to electricity. Dialogue: 0,0:00:22.00,0:00:27.00,Default,,0000,0000,0000,,One of the most evident effects of electricity are attractions and repulsions Dialogue: 0,0:00:27.00,0:00:34.00,Default,,0000,0000,0000,,of electrified bodies and this is important because you can use these forces Dialogue: 0,0:00:34.00,0:00:37.00,Default,,0000,0000,0000,,to produce work, to produce energy. Dialogue: 0,0:00:37.00,0:00:43.00,Default,,0000,0000,0000,,We can start understanding it with an analogy with gravity, which is simple Dialogue: 0,0:00:43.00,0:00:47.00,Default,,0000,0000,0000,,because we have only attraction and electricity is much more complicated because Dialogue: 0,0:00:47.00,0:00:50.00,Default,,0000,0000,0000,,you have also this complication of repulsion. Dialogue: 0,0:00:50.00,0:00:56.00,Default,,0000,0000,0000,,If I have a body of mass, there is an attraction between the body and the earth Dialogue: 0,0:00:56.00,0:00:59.00,Default,,0000,0000,0000,,and there is potential energy. Dialogue: 0,0:00:59.00,0:01:04.00,Default,,0000,0000,0000,,If I drop this body, it has the capacity to produce some work Dialogue: 0,0:01:04.00,0:01:08.00,Default,,0000,0000,0000,,maybe to break a neck down there. Dialogue: 0,0:01:08.00,0:01:12.00,Default,,0000,0000,0000,,It goes down and the potential energy diminishes Dialogue: 0,0:01:12.00,0:01:17.00,Default,,0000,0000,0000,,and it acquires kinetic energy, movement, velocity, Dialogue: 0,0:01:17.00,0:01:21.00,Default,,0000,0000,0000,,and which is proportionate to the square of velocity. Dialogue: 0,0:01:21.00,0:01:27.00,Default,,0000,0000,0000,,With electricity, it's more complicated because of repulsion but the idea is similar. Dialogue: 0,0:01:27.00,0:01:32.00,Default,,0000,0000,0000,,You can use the interactions between electrified borders between charges Dialogue: 0,0:01:32.00,9:59:59.99,Default,,0000,0000,0000,,to produce work so to have energy to produce something.