Pratica di Shadowing: 2.7K - Impara a parlare inglese con YouTube
C1
⏸ In Pausa
In 1827, a German high school teacher discovered what he called a pure law of nature.
162 frasi
Se le frasi sono troppo corte o troppo lunghe, clicca su Edit per modificarle.
1
In 1827, a German high school teacher discovered what he called a pure law of nature.
2
But when he published his findings, he was first ridiculed, then completely ignored.
3
One professor said it was a web of naked fancies, and the result of an incurable delusion.
4
Another said it was an unmistakable failure, and that anyone who preached such heresies was unworthy to teach science.
5
The criticism got so bad, he eventually resigned his position and moved to another city 400 kilometers away.
6
About 15 years later though, the Royal Society of London would recognize his work and award him the Copley Medal,
7
essentially equivalent to the modern Nobel Prize.
8
And today, this same law is taught to teenagers across the world as the fundamental principle of electronics.
9
Georg Ohm was born in 1789 in Erlangen, Bavaria to a modest working-class family.
10
His father was a locksmith who had no formal education but loved math and philosophy with a deep passion.
11
He educated himself to such a high degree
12
that he was able to provide an excellent education to Georg and gave him a strong foundation in both math and science.
13
Eventually, in 1804, Ohm went off to study at the University of Erlangen.
14
This would last only three semesters, though.
15
While attending university, he spent much of his time pursuing non-academic interests, to the dismay of his father,
16
who withdrew his financial support and forced his son to drop out.
17
Over the next decade or so, Ohm took up a wide number of math teaching posts in various cities across modern-day Switzerland and Germany.
18
He was eventually able to finish his university degree
19
and settled into a permanent role as a high school science teacher at the Jesuit Gymnasium of Cologne,
20
a top-rated institution that was better than any Ohm had previously taught in.
21
Most importantly, the school had something that Ohm would use to dramatically alter his life, a well-funded laboratory.
22
Ohm began his teaching position in 1817.
23
Around this point in history, the theory of static electricity was well developed.
24
The understanding of moving charges, or current on the other hand, was still in its early stages.
25
The units of a volt or an amp did not exist yet, and there was no consistent calibrated way to measure current.
26
The prevailing idea about observed electric forces was that they consisted of the action of some sort of electrical fluid.
27
There were three discoveries in the early 1800s, though, that fundamentally changed this understanding of electricity.
28
And while Ohm initially used his school's lab as an aid to teaching, these three discoveries also convinced him to devote his spare time conducting research in the lab.
29
And it enabled him to systematically study and experiment with electricity.
30
The first of these discoveries was the battery, invented by an Italian scientist named Alessandro Volta in 1800.
31
Volta provided a convenient, relatively easy way for scientists to create a continuous flow of electricity.
32
All one had to do was take a stack of alternating copper and zinc plates.
33
Between each layer, place a piece of cloth soaked in brine.
34
This would generate an electric force.
35
and by connecting the top and bottom plates with a wire, an electric current would be produced.
36
Volta's invention came to be called the voltaic pile and it was pivotal in the process of understanding what electricity is.
37
Before this, scientists were only able to create temporary sparks.
38
Now, scientists of all kinds were able to create a continuous electric current
39
and use it to conduct experiments in entirely new ways.
40
The voltaic pile would eventually allow Michael Faraday to conduct his famous experimental work
41
that would lead to the four equations of electromagnetism.
42
But before that, there was another pivotal discovery by the Danish scientist Hans Christian Orsted.
43
In 1820, after setting up a voltaic pile, Orsted placed a magnetic compass nearby.
44
To his surprise, he saw that the needle moved.
45
After repeating the experiment several times with magnets in various locations, he observed that the magnets formed a circle around the wire.
46
Somehow the current flowing through the wire was causing a magnetic force around it.
47
The first link between electricity and magnetism was discovered.
48
Both Folta's and Orsted's discoveries played a pivotal role in Ohm's initial experiments with electricity.
49
The third discovery, which I'll mention shortly, provided the final solution to some of the difficulties Ohm encountered along the way.
50
Ohm began his experimental studies by first deciding to study the conductivity of various metals.
51
Most scientists at the time were convinced that the voltage in a battery
52
and the current that flowed in a wire were completely independent phenomena.
53
Ohm believed otherwise.
54
He was convinced that the two were linked by some physical law and he was determined to discover it.
55
He began by setting up a voltaic pile and connecting it to a torsion balance, an early form of an ammeter.
56
Essentially it consisted of a magnetic needle that would move more or less strongly depending on the strength of the current.
57
He experimented with wires of different materials like copper, gold, silver, and brass.
58
He also varied the lengths of wires, but made sure all of them had the same diameter.
59
Ohm found that the following materials with their corresponding lengths were all equally conductive,
60
but he couldn't find the deeper connection between voltage and current that he was really after.
61
The reason?
62
His source of power, the voltaic pile.
63
Though Volta's invention provided a much needed advance in providing a continuous current to scientists at the time, the performance of these batteries was anything but perfect.
64
The current quickly dissipated over time.
65
In fact, when Ohm conducted his experiment, he used the standard wire as his control
66
and then he would switch various wires in
67
and compare the current strength with it versus the current strength with the standard wire.
68
There was a big problem though.
69
The standard wire kept experiencing a smaller and smaller current over time.
70
He decided to attempt to calculate what he termed as the loss of force here, and he came up with this equation.
71
But after making slight adjustments and repeating this experiment a few times in different ways,
72
he realized he needed a better method.
73
The rate of decay of the battery was just too unpredictable, and the equation he initially found didn't consistently fit the data.
74
At the suggestion of a colleague named Johann Christian Paggendorf, He decided to replace the voltaic pile with a thermocouple.
75
This was the third key discovery that enabled Ohm to make his own scientific breakthrough.
76
Now, before I explain how the thermocouple led to Ohm's breakthrough, I'd like to take a minute to thank this video's sponsor, Odoo.
77
Odoo is an all-in-one management software that gives creators, businesses, and entrepreneurs tools to simplify their day-to-day management.
78
They have a ton of easy to use applications designed specifically to meet all your business needs and streamline your workflow.
79
If you need systems that handle taxes, invoicing and sales, or even full website creation and more,
80
Odoo can handle it all in one place.
81
No more duct taping and having to manually coordinate between various apps.
82
Just one streamlined system that helps you operate more efficiently, so you can focus on what actually matters.
83
And as your business or your team grows, you can easily add new tools.
84
So Odoo can grow along with you at your pace.
85
The best part is that your first app with Odoo is completely free for life and it includes unlimited hosting and support.
86
You can also try it risk-free with a 15-day free trial.
87
No credit card required.
88
Just click the link down below.
89
Now back to the thermocouple.
90
The thermocouple was discovered by a German physicist named Thomas John Seebeck in 1822.
91
Seebeck found that if he made a circuit with two different metals, he could cause a magnetic needle to be deflected.
92
In other words, he could produce a steady electric current.
93
Crucially though, this only occurred when there was a temperature difference between the two.
94
So one metal had to be either heated up or cooled.
95
Heating would cause the needle to go in one direction, whereas cooling resulted in a deflection in the opposite direction.
96
In order to use a thermocouple as his power source, Ohm had to slightly change his experimental setup.
97
He began by creating his own thermocouple with bismuth and copper.
98
He then placed two containers underneath, one filled with boiling water and the other filled with ice.
99
This created a constant 100 degree temperature difference between the two.
100
Finally, he connected all of this to two cups filled with mercury, and he also attached a torsion balance to measure the strength of current again.
101
The cups of mercury were the means by which he connected the circuit.
102
When he would place a wire inside the cup, the circuit would close and current would flow.
103
When he removed it, the circuit would open and the current would stop.
104
The thermocouple was exactly what he needed.
105
It provided a continuous, reliable current.
106
He then tested eight wires of varying lengths and recorded the deflection of the needle for each one.
107
He found the following results.
108
Ohm then stated that the above numbers can be represented very satisfactorily by the equation x equals a over b plus x.
109
Where big x is the strength of the magnetic effect of the wire, little x is the length of the wire, and according to him, a and b are constants
110
that depend on the exciting force and resistance of the remaining parts of the circuit.
111
In other words, a and b depended on both the wire's material and the source of power.
112
He then decided to make the temperature difference smaller to see how this would affect his results.
113
He found that B was not affected at all by this change, but A was.
114
Ohm concluded that A depended purely on the exciting force and B depended purely on the resistance of the circuit.
115
He had just discovered what we today call Ohm's law.
116
In modern notation, we call the magnetic effect the current, A the voltage, and the denominator here is the resistance.
117
Ohm wrote up all these results in a paper published in 1826, but he wasn't done just yet.
118
You see, a few years prior to this, a French mathematician by the name of Joseph Fourier published a revolutionary book on heat that included,
119
among other things, the invention of Fourier series and the heat equation.
120
Ohm had been deeply impressed by Fourier's work
121
and wanted to provide the same type of rigorous mathematical framework to the physical law he'd just discovered through experiment.
122
He spent the next year developing a purely mathematical theory that made very little reference to his experiments.
123
He then published his new theory in 1827 in a book titled The Galvanic Circuit Investigated Mathematically.
124
In it he described electricity very much like Fourier described heat.
125
And he even mathematically derived a new version of his law that looks even more like the modern version today.
126
But as I mentioned at the beginning of the video, this work was not well received by the scientific community surrounding Ohm.
127
A prominent professor in Berlin named Heinrich Wilhelm Dov said it was a naked web of fancies.
128
Another Berlin professor named Georg Friedrich Pohl called it an unmistakable failure
129
and even convinced the German minister of education to pressure Ohm to resign, which he ultimately did.
130
All this occurred for many reasons, but to give you a bit of insight into why this seemingly strange situation came about,
131
here are two factors that played a significant role.
132
First, most German physicists at the time were philosophically opposed to mathematically deductive physical theories.
133
They thought it wasn't an accurate way to discover and understand the laws of physics.
134
What they preferred instead was a focus on performing experiments and letting experimental results guide their understanding of theory.
135
It seems that the later mathematical theory that Ohm developed was the primary contact many had with his work,
136
and they were unaware of his earlier experimental results.
137
As a consequence, they simply did not appreciate its emphasis on math and lack of contact with experiment.
138
The second reason was the way in which Ohm wrote.
139
He seems to have lacked the ability to communicate his ideas in a clear way that others could understand.
140
Though he began his treatise explaining all the math he was using, most of it was just completely unfamiliar and confusing to his readers.
141
As one author wrote about Ohm's book, in neither the introduction nor the body of the work did
142
Ohm bring decisively home either the underlying unity of the whole or the connections between fundamental assumptions and major deductions.
143
After being forced to resign from his permanent position in Cologne, Ohm took up various temporary teaching positions at schools in Berlin.
144
Eventually, in 1833, he was able to become a professor at Nuremberg Polytechnic.
145
It was only after scientists from other countries discovered Ohm's work
146
and began promoting it that he finally got the recognition that he deserved.
147
In particular, William Sturgeon and Charles Wheatston, two scientists from England who promoted Ohm's ideas,
148
as well as Claude Pouillet from France who independently confirmed Ohm's results.
149
This eventually led to proper recognition in his homeland as well.
150
In June 1839, he became a member of the Prussian Academy of Sciences.
151
Then in 1841, he was given the Copley Medal by the Royal Society in London, essentially the Nobel Prize of his day.
152
And finally in 1852, he achieved something that was his lifelong ambition.
153
He was appointed the Chair of Physics at the University of Munich,
154
which he sadly would hold for just two years as he passed away in 1854 due to a stroke.
155
Years after his death, he would receive an honor that would make him ever present in the scientific community.
156
In 1881, when the International Congress in Paris was establishing a system of electric units.
157
They defined the amp, the volt, and the ohm.
158
To this day,
159
this unit of measurement together with Ohm's law are used by millions of students worldwide as the cornerstone of analyzing electrical circuits.
160
If you'd like to see more videos like this, join my Patreon community and support the channel by clicking right here.
161
And thank you to all the generous patrons who make these videos possible.
162
Thank you.
Scarica l'app
Everything you need to speak fluently
AI PronunciationScore every sentence
IPA PracticeMaster every sound
VocabularyBuild your word bank
Vocab GameLearn while playing
About This Lesson
In questa lezione, praticherai l'ascolto e la pronuncia inglese usando un video che racconta la storia di Georg Ohm e le sue scoperte nel campo dell'elettricità. Imparerai a seguire un discorso fluido, con dettagli scientifici e cronologici, e a migliorare la tua capacità di ripetere frasi in tempo reale. È un'ottima occasione per combinare la passione per la scienza con l'approfondimento della lingua inglese: perfetto per chi vuole imparare l'inglese con YouTube e migliorare sia la comprensione che la pronuncia.
Parole chiave e frasi utili
- Voltaic pile: "Pila voltaica" (l'invenzione di Volta per generare corrente elettrica)
- Electric current: "Corrente elettrica" (flusso di cariche elettriche)
- Magnetic force: "Forza magnetica" (l'azione del magnete sul filo conduttore)
- Conductivity: "Conduttività" (capacità di un materiale di trasmettere l'elettricità)
- Ridiculed: "Ridotto in ridicolo" (come fu Ohm all'inizio delle sue ricerche)
- Fundamental principle: "Principio fondamentale" (il legame tra tensione, corrente e resistenza insegnato oggi in scuola)
Consigli per la pratica
Il video ha un tono informativo e una velocità media, perfetto per esercitarti con lo shadow speech. Ecco come fare: riproduci un frammento di 10-15 secondi, poi metti in pausa e ripetilo immediatamente, cercando di seguire l'intonazione e la velocità dell'oratore. Concentrati sulle parole lunghe come "electromagnetism" o "calibrated": ripetile più volte per migliorare la pronuncia inglese. Se trovi difficoltà, usa lo "shadowspeaks" come tecnica: ascolta il frammento, poi ripètilo a voce alta, cercando di "ombreggiare" il suono. Per la pratica di conversazione in inglese, racconta a un amico la storia di Ohm usando le frasi apprese: così combinerai la comprensione con la produzione linguistica. Ricorda: la chiave è la costanza, anche 10 minuti al giorno ti aiuteranno a progredire!
Cos'è la tecnica dello Shadowing?
Shadowing è una tecnica di apprendimento delle lingue supportata da studi scientifici, originariamente sviluppata per la formazione dei traduttori professionisti e resa popolare dal poliglotta Dr. Alexander Arguelles. Il metodo è semplice ma potente: ascolti un audio in inglese di madrelingua e lo ripeti immediatamente ad alta voce — come un'ombra che segue il parlante con un ritardo di solo 1–2 secondi. A differenza dell'ascolto passivo o degli esercizi di grammatica, lo shadowing costringe il tuo cervello e i muscoli della bocca a elaborare e riprodurre simultaneamente i modelli di discorso reale. La ricerca dimostra che migliora significativamente la precisione della pronuncia, l'intonazione, il ritmo, il discorso connesso, la comprensione dell'ascolto e la fluidità del parlato — rendendolo uno dei metodi più efficaci per la preparazione alla prova di speaking dell'IELTS e per la comunicazione reale in inglese.