Практика Shadowing: Current | Introduction to electrical engineering | Electrical engineering | Khan Academy - Изучайте разговорный английский по видео
Выберите режим практики
Каждый режим открывает полноэкранную комнату практики.
118 предложений
Если предложения слишком короткие или длинные, нажмите Edit, чтобы их изменить.
1
All right, now we're going to talk about the idea of an electric current.
2
And the story about current starts with the idea of charge.
3
So we've learned that we have two kinds of charges, positive and negative charge.
4
We'll just make up two little charges like that.
5
And we know if they're the opposite sign, that there will be a force of attraction between them.
6
And if they have two like signs, here's two charges that are both positive.
7
And these charges are going to repel each other.
8
So this is the basic electrostatics idea.
9
And the same thing for two minus charges.
10
They also repel.
11
So like charges repel and unlike charges attract.
12
That's one idea.
13
So we have the idea of charge.
14
And now we need a place to get some charge.
15
And one of the places we'd like to get charge from is copper, copper wires.
16
A copper atom looks like this.
17
A copper atom has a nucleus with some protons in it.
18
And it also has electrons flying around the outside, electrons in orbits around the outside.
19
So we'll draw the electrons like this.
20
So there will be orbits around this nucleus.
21
Pretty good circles.
22
And there will be electrons in these little minus signs.
23
There's electrons stacked up in this.
24
And even farther out, there's electrons.
25
So there's a kind of an interesting -looking copper atom.
26
Copper, the symbol for copper is Cu, and its atomic number is 29.
27
29. That means there's 29 protons inside here, and there's 29 electrons outside.
28
And it turns out, just as a coincidence for copper, that the last orbital out here has just one electron in it.
29
That guy right there.
30
And that's the one that is the easiest to pull away from copper and have it go participate in conduction,
31
in electric current.
32
So if I have a chunk of copper,
33
every copper atom will have the opportunity to contribute this one lonely electron out here.
34
If we look at another element like, for instance, silver, silver has this same kind of electron configuration where there's just one out here.
35
And that's why silver and copper are such good conductors.
36
Alright, so now we're going to build, let's build a copper wire.
37
Here's sort of a copper wire.
38
It's just made of solid copper, it's all full of copper atoms.
39
And I'm going to put a voltage across this.
40
There's our little battery.
41
This is the minus sign, this is the plus sign.
42
and we'll hook up a battery to this.
43
And what's going on in here,
44
inside this copper, inside this copper is a whole bunch of electrons that are associated with atoms.
45
It's a neutral, it's a neutral piece of metal.
46
There's the same number of protons as there is electrons.
47
But these electrons are a little bit loose.
48
So if I put a plus over here, that's this situation right here where a plus is attracting a minus.
49
And so an electron is going to sort of wander over this way and go like that.
50
And that's going to leave sort of a net positive charge in this region.
51
And so these electrons are all going to start moving in this direction.
52
And down at the end, here, an electron is going to come out of this battery,
53
travel in here, and it's going to go in there and make up the difference.
54
So if I had a net positive charge here from the electrons leaving and going to the left, this battery would fill those in.
55
And I'm going to get a net movement of charge, of negative charge, around in this direction like this.
56
The question is, how do I measure that?
57
How do I measure or give a number to that amount of stuff that's going on?
58
So we want to quantify that.
59
We want to assign a number to the amount of current happening here.
60
So what we do is in our heads, we put a boundary across here.
61
So just make that up in your head.
62
And it cuts all the way through the copper.
63
And what we know, we're going to stand right here.
64
And we're going to keep our eye right on this boundary down in here.
65
And as we watch, what we're going to do is we're going to count the number of electrons that move by here.
66
And we're going to have a stopwatch, and we're going to time that.
67
And so we're going to get, basically, this is charge.
68
It's negative charge, and it's moving to the side.
69
And what we're going to do is at one little spot right here, we're just going to count the number that go by in one second.
70
And so we're going to get charge per second.
71
And it's going to be a negative charge moving by.
72
And that's what we call current.
73
and it's the same as water flowing by in a river that's the same idea
74
all right now I'm going to set up a different situation
75
that also get produces a current and this time we're going to do it with water water and salt
76
so here's here's just let's build a tube of salt of salt water like this so we're going to pretend
77
Again, this is some tube that's all full of water.
78
I'm also gonna put a battery here.
79
Let's put another battery.
80
And we'll stick the wire into there, and we'll stick the wire into there.
81
And this is the plus side of the battery, and this is the minus side of the battery.
82
So water is H2O, and this does not conduct.
83
There's no free electrons available here.
84
But what I'm gonna do is I'm gonna put some table salt in it.
85
This is ordinary salt that you put on your food, and it's made of sodium.
86
That's the symbol for sodium.
87
And chloride, Cl is chloride.
88
Sodium chloride is table salt.
89
If we sprinkle some table salt into water, what happens is these dissolve,
90
and we get a net plus charge here and a net minus charge on the chlorine.
91
So out here is floating around NAs with plus signs and CLs nearby, really close nearby, with minuses.
92
Let's keep it even, all right.
93
Now when I dip my battery wires into this water, what's going to happen is this plus charge,
94
this plus charge over here from the battery is going to attract the minus CLs.
95
So the CL is going to move that way a little bit.
96
And over here, the same thing is happening.
97
There's a minus sign here.
98
There's a minus from the battery.
99
And that's going to attract this, and it's also going to repel the Cl minuses.
100
And so what we get is a net motion of positive charge plus Q going this way,
101
and we get minus Q going this way.
102
And how do we measure that current?
103
How do we measure that current?
104
Well, we do it the same way as we did up there with copper.
105
We put a boundary through here in our heads.
106
We stand here, and we watch the charges moving by.
107
And what we're going to get is some sodiums, Na's, moving this way, and chlorines moving this way,
108
just like we showed here.
109
Na moving this way.
110
And so there's going to be plus charges moving through the boundary
111
and minus charges moving through the boundary in the opposite direction.
112
And if I take the total sum of that, for example, if I see one
113
Na go this way and one Cl go this way, that's equivalent to two charges moving through the boundary.
114
Hope that makes sense.
115
It's equivalent to two charges, one going this way and one going this way.
116
And because they have opposite signs, they add together and make two charges.
117
In this case, current is equal,
118
again, to charge per second.
Скачать приложение
Всё для свободной речи
ИИ-оценка произношенияОценка каждой фразы
Практика IPAОсвойте каждый звук
СловарьСоберите свой словарный запас
Игра со словамиУчитесь играя
Тот же канал
B11
Introduction to ratios | Ratios, rates, and percentages | 6th grade | Khan Academy
Daily ConversationHigh School Students
B16
LearnStorm Growth Mindset: How to write a SMART goal
American AccentBusiness EnglishHigh School StudentsUniversity Students
B19
States of matter | Middle school chemistry | Khan Academy
American AccentTOEFL PrepCambridge Exam PrepHigh School Students
B12
Newton's second law | Middle school physics | Khan Academy
American AccentHigh School StudentsUniversity Students
C15
Molecules, crystals, and diatomic elements | Middle school chemistry | Khan Academy
American AccentHigh School StudentsUniversity Students
B13
Atoms | Middle school chemistry | Khan Academy
American AccentTOEFL PrepCambridge Exam PrepHigh School Students
C13
Pixar in a Box | Welcome to Pixar in a Box | Khan Academy
American AccentHigh School StudentsUniversity Students
C14
Proportional reasoning with motion | AP Physics | Khan Academy
American AccentBusiness EnglishUniversity StudentsWorking Adults
C12
Biology overview
American AccentUniversity Students
C12
Newton, Leibniz, and Usain Bolt | Derivatives introduction | AP Calculus AB | Khan Academy
American AccentCambridge Exam PrepUniversity StudentsWorking Adults
B12
Elements | Middle school chemistry | Khan Academy
American AccentHigh School StudentsUniversity Students
C115
Introduction to high school physics | Khan Academy
American AccentHigh School StudentsUniversity Students
B12
Introduction to interest | Interest and debt | Finance & Capital Markets | Khan Academy
American AccentBusiness EnglishUniversity StudentsWorking Adults
C14
Derivative as slope of a tangent line | Taking derivatives | Differential Calculus | Khan Academy
American AccentCambridge Exam PrepUniversity StudentsWorking Adults
B2How to rationalize a denominator | Exponent expressions and equations | Algebra I | Khan Academy
Daily ConversationHigh School Students
FOR YOU
Рекомендуемое видео
B21
183 предложений
Concept of Electric Current with Train example | TheElectricalGuy
Daily ConversationUniversity Students
C11
29 предложений
What are Ionic Bonds? | Properties of Matter | Chemistry | FuseSchool
Daily ConversationUniversity Students
C12
77 предложений
What is Voltage?
Daily ConversationUniversity Students
![[Lecture Ready3] Ch10 Lecture2](https://img.youtube.com/vi/8FVVfebHarQ/mqdefault.jpg)
C11
111 предложений
[Lecture Ready3] Ch10 Lecture2
Daily ConversationUniversity Students
C1378 предложений
How To Wire a House Main Electrical Panel Load Center & Layout Tips Full Step By Step Process 200Amp
Daily ConversationUniversity StudentsWorking Adults
C1552 предложений
The Professor Who Taught People How To Think (1962)
Daily ConversationUniversity StudentsWorking Adults
C13
279 предложений
LET THERE BE... Voltage? | Maxwell's Equation #2 Explained for Beginners
Daily ConversationUniversity Students
C11
86 предложений
The Composition and Function of Blood
Daily ConversationUniversity Students
C11
193 предложений
Semiconductors explained in 16 mins | Chris Miller
Daily ConversationUniversity StudentsWorking Adults
C11
176 предложений
Every Networking Concept Explained | Networking 101 (2026)
Daily ConversationUniversity StudentsWorking Adults
C11
91 предложений
Why is water H₂O, not H₂O₂? | Lesson 7: Valency and Chemical Formulae | Science in English
Daily ConversationUniversity Students
C12
28 предложений
What is IMC (Intermetallic Compounds) part II? The different between IMC, alloy, eutectic
Daily ConversationUniversity StudentsWorking Adults
Лексика и советы по произношению к этому уроку
Чаще всего повторяются слова: charge, copper, electron, minus, battery. В этом видео 118 предложений и 1319 слов для шедоуинга. Речь длится 9:15. Говорящий держит ровный темп — около 143 слов в минуту, удобный для шедоуинга. 85% слов входят в 3000 самых частых слов английского языка; остальные стоит разобрать перед занятием.
Ключевая лексика этого видео
15 слов из видео, которые стоит выучить, с произношением и значением:
| Слово | Произношение | Значение |
|---|---|---|
| copper существительное | /ˈkɒpə/ | медь |
| minus | /ˈmaɪ.nəs/ | ми́нус |
| wire существительное | /ˈwaɪɚ/ | про́волока, про́вод |
| boundary существительное | /ˈbaʊndɹi/ | грани́ца, межа́ |
| atom существительное | /ˈætəm/ | а́том |
| electron существительное | /ɪˈlɛk.tɹɑn/ | электро́н |
| attract глагол | /əˈtɹækt/ | притя́гивать, притяну́ть |
| sodium существительное | /ˈsəʊ.di.əm/ | на́трий |
| tube существительное | /tuːb/ | тю́бик |
| symbol существительное | /ˈsɪmbəl/ | си́мвол, знак |
| neutral прилагательное | /ˈnuː.tɹəl/ | нейтра́льный |
| orbit существительное | /ˈɔɹ.bɪt/ | орби́та |
| nucleus существительное | /ˈnuː.kli.əs/ | ядро́, центр |
| element существительное | /ˈɛləmənt/ | элеме́нт, звено́ |
| ordinary прилагательное | /ˈɔɹdɪnɛɹi/ | обыкнове́нный, обы́чный |
Фразовые глаголы, которые вы услышите
| Слово | Произношение | Значение |
|---|---|---|
| make up глагол | /ˌmeɪk ˈʌp/ | составля́ть, соста́вить |
| set up глагол | /ˌsɛt ˈʌp/ | устана́вливать, установи́ть |
| turn out глагол | ока́зываться, оказа́ться |
Фразы, которые стоит повторять
Короткие законченные фразы из видео, которые пригодятся в повседневном разговоре:
- We'll just make up two little charges like that.
- The question is, how do I measure that?
- I'm also gonna put a battery here.
- Let's keep it even, all right.
- How do we measure that current?
Произношение, на которое стоит обратить внимание
Говорящий использует 32 сокращённых и редуцированных форм, например we're, I'm, we'll. Произносите их коротко, так, как слышите.
- Звуки «sh» и «zh»: associate /əˈsoʊʃi.ət/, attraction /əˈtɹækʃn̩/, configuration /kənˌfɪɡ.əˈɹeɪ̯.ʃən/, conduction /kənˈdʌkʃən/
- Длинные слова — следите за ударением: ordinary /ˈɔɹdɪnɛɹi/, participate /pɑːˈtɪs.ɪ.peɪt/, associate /əˈsoʊʃi.ət/, configuration /kənˌfɪɡ.əˈɹeɪ̯.ʃən/, coincidence /kəʊˈɪnsɪdəns/
Звуки, трудные для русскоязычных:
- /w/ — губы округлены, это не /v/: wire /ˈwaɪɚ/, wander /ˈwɑndɚ/, quantify /ˈkwɑn.tɪˌfaɪ/
- Звонкие согласные в конце слова — не оглушайте их: tube /tuːb/, pretend /pɹəˈtɛnd/, voltage /ˈvəʊltɪd͡ʒ/, chloride /ˈklɔɹˌaɪd/, dissolve /dɪˈzɑlv/
Как заниматься с этим видео
- Прослушайте всё видео один раз молча и выпишите незнакомые слова.
- Повторяйте предложение за предложением на обычной скорости, пока ваш ритм не совпадёт с ритмом говорящего.
- Запишите себя и сравните с оригиналом, обращая внимание на такие слова, как copper, minus, wire.
Что такое техника Shadowing?
Shadowing — это научно обоснованная техника изучения языка, изначально разработанная для подготовки профессиональных переводчиков и популяризированная полиглотом доктором Александром Аргуэльесом. Метод прост, но эффективен: вы слушаете аудио на английском от носителей языка и немедленно повторяете вслух — как тень, следующая за говорящим с задержкой в 1–2 секунды. В отличие от пассивного прослушивания или грамматических упражнений, Shadowing заставляет мозг и мышцы рта одновременно обрабатывать и воспроизводить реальные речевые паттерны. Исследования показывают, что это значительно улучшает точность произношения, интонацию, ритм, связную речь, понимание на слух и беглость речи — что делает его одним из самых эффективных методов для подготовки к IELTS Speaking и реального общения на английском.