WEBVTT 00:00.000 --> 00:07.401 Laure wants to know how the batteries work! 00:07.401 --> 00:16.494 Constituted of different materials with respect to their charges (electrons), they produce by oxydoreduction a chemical effect generating an electrical voltage 00:16.494 --> 00:23.579 But what is a tension? 00:23.579 --> 00:30.653 The tension is a gap! We'll use a potato! 00:30.653 --> 00:39.794 But it's a real potato? Yes, we can even eat it but after :-) 00:39.794 --> 00:49.316 I inserted a copper wire and an iron nail into the potato: I read 0.49 or 0.5 Volt! 00:49.316 --> 00:55.811 With 3 potatoes I will have like the battery: 1.5 Volt! 00:55.811 --> 01:03.123 Laure wants to run her hair dryer with potatoes! 01:03.123 --> 01:13.524 NO ! unlike some 'fakes'; there is not enough intensity and therefore power! 01:13.524 --> 01:18.537 Watch out for the poison on videos! But what is the use of potatoes? To understand the principle 01:18.537 --> 01:31.506 The potato shows the principle of the pile. Volta used copper, zinc and soaked cloth 01:31.506 --> 01:43.690 We will look at the digital oscilloscope, currently connected to display 0 deviation 01:43.690 --> 01:49.316 The noise (including the 50 Hz electrical network) 01:49.316 --> 02:00.779 One observes 0.5 volts of difference between the lines (signals) red + and blue the reference 02:00.779 --> 02:13.609 This deviation is called ddp: potential difference or voltage 02:13.609 --> 02:26.774 This difference is constant (except discharge) and if I reverse, the difference is reversed 02:26.774 --> 02:41.885 The direction depends on where the reference of the measuring instruments is connected! 02:41.885 --> 02:48.341 There is continuous (smooth) current: it does not change direction! 02:48.341 --> 02:53.687 Laure wants to know what the alternative is! 02:53.687 --> 03:01.506 To simplify, we now have on the screen an alternating current: sometimes positive, sometimes negative 03:01.506 --> 03:15.383 But this zig-zag corresponds to what? 03:15.383 --> 03:25.679 It is like a continuous current, but it will increase, decrease, reverse ... 03:25.679 --> 03:35.244 The batteries produce a chemical reaction that can not change direction: only continuous 03:35.244 --> 03:45.453 The industrial current comes from the transformation of a rotation in current 03:45.453 --> 03:51.751 So rotation = change of direction = alternative most of the time! 03:51.751 --> 04:16.006 All the stored electricity is continuous! Batteries, batteries ... You can not store a movement 04:16.006 --> 04:32.999 The solar panels produce continuous, if not wind, turbines ... alternating ~ 04:32.999 --> 04:52.000 Laure wants to know how one gets 1.5 V, 9 V, 12 Volts ... 04:52.000 --> 04:57.737 Batteries 1.5 Volt and rechargeable battery 1.2 Volts 04:57.737 --> 05:11.970 A 9 Volt battery (we'll see 6 * 1.5) and a 12 Volt battery 05:11.970 --> 05:20.531 Voltmeter and oscilloscope in parallel: one reads 1.65 Volt the red line has risen as much 05:20.531 --> 05:28.310 This one: 9.78 Volts, the line, oscilloscope signal is almost 10 V 05:28.310 --> 05:38.042 But tell me Laure, how do we go from 1.5 V to 9 V with the same materials? 05:38.042 --> 05:43.275 Laure asks why sometimes we install 2 batteries? 05:43.275 --> 05:52.314 I have 1.5 flights in each, so I put them to the 'leu-leu' line in series: what will I have? 05:52.314 --> 06:05.764 In series, I get 1.6 + 1.6 = 3.2 Volts! 06:05.764 --> 06:17.644 More practical: I use the coupler in order to achieve the same result! 06:17.644 --> 06:33.339 So how much to get to 9 Volts? 06:33.339 --> 06:44.227 Thus, 6 elements 1.5 V in series, offer 9 V! 06:44.227 --> 06:53.712 Laure says that in the battery there are 8 elements 1.5 V: 8 * 1.5 = 12 Volts! 06:53.712 --> 07:09.247 But the battery is leaded which offers 2 Volts per element ... 07:09.247 --> 07:16.536 It therefore consists of only 6 elements: 6 * 2 = 12 Volts 07:16.536 --> 07:29.206 12.6 Volts. So much for this little introduction! Thank you all!