쉐도잉 연습: What is Voltage? - 영상으로 영어 말하기 배우기

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To understand how electricity works, we need to zoom in on atoms, the things that make up all matter.

Atoms are made up of three basic particles.

That is, protons, which have a positive electric charge, neutrons, which have no electric charge, and electrons, which have a negative electric charge.

The protons and neutrons are tightly packed in the core or nucleus of an atom,

while electrons move about this nucleus in regions known as shells or orbitals.

Right now, this atom is electrically neutral, as it has the same number of protons and electrons.

With enough energy, an electron may be stripped away, leaving the atom with a net positive charge.

Likewise, another atom may receive a freed electron, which then makes the atom electrically negative.

When we have two objects with different electric charges due to the absence or presence of excess electrons, we say that we have static electricity.

We can demonstrate this using a balloon and a soda can.

When I rub a piece of cloth against the balloon, I strip away electrons from the piece of cloth and add them to the balloon.

As a result, this balloon now has a net negative charge.

When we bring it close to the can, the can chases the balloon.

Let's look at why that's happening.

The aluminum in the can is a conductor, which means that the electrons can freely move about the material.

As we bring the negatively charged balloon near the metal, the electrons are pushed away to the far side of the can since like charges repel.

That leaves an excess of positive charge on the side of the can nearest the balloon, which is pulled toward the balloon as opposite charges attract.

Since the positive charges are closer to the balloon than the negative charges, the attractive force is greater than the repulsive force.

This results in a net force that pulls the can toward the balloon.

Let's see that again in instant replay.

Before we go any further, let's talk about units.

The SI unit for electric charge is the coulomb, generally abbreviated with an uppercase C.

An electron has a charge of about negative 1 .602 times 10 to the negative 19th coulombs,

and a proton has a charge of about positive 1 .602 times 10 to the negative 19th coulombs.

Energy is usually given in joules, which is abbreviated with the symbol uppercase J.

1 joule is equal to the amount of energy transferred to an object

when a force of 1 newton is applied to that object over a distance of 1 meter.

Energy can either be potential, which results from an object's position or arrangement, or kinetic, resulting from the object's motion.

Both kinetic and potential energy are given in joules.

Now we can define voltage.

Voltage is a measure of electric potential between two points.

The unit, volt, is defined as one joule of potential energy per unit charge given in coulombs.

Let's explain this with an example.

Let's say that I've got a particle with a negative one coulomb of charge.

Then, let's say there is a particle with positive one coulomb of charge next to it.

Since opposites attract and the positive particle is as close as it can get to the negative particle, everything is at rest.

There is no kinetic or potential energy.

Now, let's say

that I need to use 10 joules of energy to move the positive particle from its resting position to this point.

If I were to release it, it would move back to the negative particle.

As a result, we can say that it has 10 joules of electric potential energy so long as I hold it here.

Now, if I repeated this demo with three positively charged particles,

it would take 30 joules of energy to move them the same distance away from the negative particle.

So they have 30 joules of potential energy as long as I'm holding them here.

As we defined earlier, voltage is the electric potential between two points.

To calculate the voltage between their starting and ending points, we know that I did 30 joules of work to move the particles,

and the total charge is 3 coulombs.

So the voltage is 30 joules divided by 3 coulombs, which is 10 volts.

We would say that the electric potential between these two points is 10 volts.

If I released one of the particles, it would move back to the negatively charged particle.

That would leave me with 20 joules of potential energy and 2 coulombs of charge, so the potential is still 10 volts.

Even if I had no positive particles, the potential between the two points is still 10 volts.

As you can see, electric potential energy is not the same as electric potential.

When we start talking about moving electrons through conductors and electronic components, we are talking about current electricity, which is slightly different than static electricity.

Let's take a look at a battery.

It doesn't really matter how far apart the terminals of a battery are.

The chemicals inside a battery determine the electrical potential between the terminals.

A fully charged AA alkaline battery is listed as having 1 .5 volts.

That means each coulomb of charge moving from one end of the battery will do 1 .5 joules of work.

Now, compare that to a much larger D -cell battery.

Each coulomb of charge will still only do 1 .5 joules of work, but a D -cell has far more coulombs of charge than a AA.

As a result, D -cells will last a lot longer than AA batteries, doing the same amount of work.

Static electricity can be a lot of fun, but more often than not, it's considered dangerous or a nuisance.

One of the most dramatic displays of static electricity happens in nature.

Storm clouds can build up a potential difference of millions of volts when compared to the Earth.

And at some point, the electrons actually force their way through the air, creating lightning in order to balance out that charge difference.

This sudden flow of electricity in an attempt to neutralize two statically charged objects is known as electrostatic discharge, or ESD.

While lightning is a rather extreme display of electrostatic buildup and discharge, static electricity can still be quite useful.

For example, many factory and power plant smokestacks employ a technology

that uses static electricity to pull soot and ash out of the air as it flows up through the pipe, resulting in less pollution.

Also, most cars are painted using a process called powder coating.

In this, paint leaving the spray nozzle is given an electric charge, and the car body is given a different electric charge,

which creates a stronger bond between the paint and the car body.

This allows for a more uniform paint coverage

and reduces paint waste since less of it's likely to stick around in the air or drip off the car body.

Next time we'll dive into current electricity and talk about making it do work for us.

Thank you.

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이 레슨의 어휘와 말하기 포인트

이 말하기 레슨은 영상 “What is Voltage?”을(를) 바탕으로 합니다. 가장 자주 반복되는 단어는 다음과 같습니다: charge, electron, energy, joule, balloon. 이 영상에는 섀도잉할 문장 48개와 단어 889개가 있습니다. 말하는 구간의 길이는 6:30입니다. 화자는 분당 약 137단어의 일정한 속도로 말해서 섀도잉하기에 편한 속도입니다. 영어에서 가장 많이 쓰이는 3,000단어에 속하는 단어가 74%뿐이라 어휘가 어려운 편입니다.

이 영상의 핵심 어휘

영상에 나오는 익혀 둘 만한 단어 15개를 발음, 뜻과 함께 정리했습니다.

단어	발음	뜻
balloon 명사	/bəˈlun/	기구, 풍선
voltage 명사	/ˈvəʊltɪd͡ʒ/	전압
particle 명사	/ˈpɑɹtək(ə)l/	입자, 립자
atom 명사	/ˈætəm/	원자, 아톰
electron 명사	/ɪˈlɛk.tɹɑn/	전자
coat 명사	/ˈkoʊ̯t/	코트, 외투
lightning 명사	/ˈlaɪt.nɪŋ/	번개, 벼락
excess 명사	/ˈɛksɛs/	우수리
attract 동사	/əˈtɹækt/	끌다, 끌어들이다
depend 동사	/dɪˈpɛnd/	의존하다, ...에 달려 있다
cloth 명사	/klɒθ/	천
minus	/ˈmaɪ.nəs/	빼기
conductor 명사	/kənˈdʌktɚ/	지휘자
nucleus 명사	/ˈnuː.kli.əs/	핵심, 핵
relative 명사	/ˈɹɛl.ə.tɪv/	친척

이 영상의 문법

화자가 가장 많이 쓰는 문형을 영상 속 실제 표현과 함께 정리했습니다.

문형	영상 속 표현
수동태 be + 과거분사 — 누가 하는지보다 무슨 일이 일어나는지에 초점	are made · may be stripped · are pushed
관계절 who / which + 절 — 사람이나 사물에 대한 추가 정보	protons, which have · conductor, which means · balloon, which is

주의할 발음

“th” 소리: thirty /ˈθɝti/, cloth /klɒθ/
“sh”와 “zh” 소리: shell /ʃɛl/, ratio /ˈɹeɪ.ʃoʊ/, pollution /pəˈluʃən/, adhesion /ˌædˈhiː.ʒən/
긴 단어 — 강세 위치에 주의: electricity /ɪˌlɛkˈtɹɪsɪti/, aluminum /əˈlu.mɪ.nəm/, positively /ˈpɑ.zɪ.tɪv.li/, abbreviate /əˈbɹi.vi.eɪt/, electrically /ɪˈlɛk.tɹɪk.li/

한국어 화자가 어려워하는 소리:

/f/ — ㅍ(/p/)으로 바꾸지 말고 윗니를 아랫입술에 대기: define /dɪˈfaɪn/, uniform /ˈjunɪˌfɔɹm/, leaf /lif/, freely /ˈfɹili/
/v/ — ㅂ(/b/)과 구별하기: voltage /ˈvəʊltɪd͡ʒ/, relative /ˈɹɛl.ə.tɪv/, divide /dɪˈvaɪd/, positively /ˈpɑ.zɪ.tɪv.li/, volt /vəʊlt/
/z/ — ㅈ이 아니라 성대를 울리는 /s/: positively /ˈpɑ.zɪ.tɪv.li/, zoom /zuːm/, exhaust /ɪɡˈzɔst/

이 영상으로 연습하는 방법

먼저 말하지 않고 영상을 끝까지 듣고 모르는 단어를 적어 둡니다.
보통 속도로 한 문장씩 섀도잉하고, 화자의 리듬과 맞을 때까지 반복합니다.
자신의 목소리를 녹음해 원본과 비교하고, balloon, voltage, particle 같은 단어에 특히 주의합니다.

쉐도잉이란? 영어 실력을 빠르게 키우는 과학적 방법

쉐도잉(Shadowing)은 원래 전문 통역사 훈련을 위해 개발된 언어 학습 기법으로, 다언어 학자인 Dr. Alexander Arguelles에 의해 대중화된 방법입니다. 핵심 원리는 간단하지만 매우 강력합니다: 원어민의 영어를 들으면서 1~2초의 짧은 지연으로 즉시 소리 내어 따라 말하는 것——마치 '그림자(shadow)'처럼 화자를 따라가는 것입니다. 문법 공부나 수동적인 청취와 달리, 쉐도잉은 뇌와 입 근육이 동시에 실시간으로 영어를 처리하고 재현하도록 훈련합니다. 연구에 따르면 이 방법은 발음 정확도, 억양, 리듬, 연음, 청취력, 말하기 유창성을 크게 향상시킵니다. IELTS 스피킹 준비와 자연스러운 영어 소통을 원하는 분들에게 특히 효과적입니다.

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쉐도잉 연습: What is Voltage? - 영상으로 영어 말하기 배우기

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