In this video we're going to be looking at capacitors to learn how they work, where we use them and why they are important.

在本視頻中，我們將瞭解電容器的工作原理、使用場合以及其重要性。

Remember electricity is dangerous and can be fatal, you should be qualified and competent to carry out any electrical work.

請記住，用電是危險的，可能會致命，您應該有資格和能力進行任何電氣工作。

Do not touch the terminals of a capacitor as it can cause an electric shock.

請勿觸摸電容器的端子，否則可能導致觸電。

So what is a capacitor?

那麼，什麼是電容器呢？

A capacitor stores electric charge.

電容器儲存電荷。

It's a little bit like a battery except it stores energy in a different way.

它有點像電池，只是儲存能量的方式不同。

It can't store as much energy as a battery although it can charge and release its energy much faster.

雖然充電和釋放能量的速度更快，但它無法像電池那樣儲存大量能量。

This is very useful and that's why you'll find capacitors used in almost every circuit board.

這一點非常有用，是以幾乎每塊電路板上都會用到電容器。

So how does the capacitor work?

那麼，電容器是如何工作的呢？

I want you to first think of a water pipe with water flowing through it.

我想讓你們首先想象一根水管，裡面有水流過。

The water will continue to flow until we shut the valve, then no water can flow.

水會一直流，直到我們關閉閥門，然後水就不會再流了。

However, if after the valve we first let the water flow into a tank, then the tank will store some of the water but we will continue to get water flowing out of the pipe.

但是，如果在閥門之後，我們先讓水流進一個水箱，那麼水箱會儲存一部分水，但我們會繼續讓水從管道中流出。

Now when we close the valve, water will stop pouring into the tank but we still get a steady supply of water out until the tank empties.

現在，當我們關閉閥門時，水會停止流入水箱，但我們仍然可以源源不斷地將水放出，直到水箱清空。

Once the tank is filled again, we can open and close the valve as many times as we like.

一旦水箱再次注滿水，我們就可以隨意開關閥門。

As long as we do not completely empty the tank, we will get an uninterrupted supply of water out of the end of the pipe.

只要我們不完全清空水箱，就能從管道末端源源不斷地供水。

So we can use a water tank to store water and smooth out interruptions to the supply.

是以，我們可以用水箱來儲水，以避免供水中斷。

In electrical circuits, the capacitor acts as the water tank and stores energy.

在電路中，電容器就像水箱一樣儲存能量。

It can release this to smooth out interruptions to the supply.

它可以釋放這種能量，以緩解供應中斷。

If we turned a simple circuit on and off very fast without a capacitor, then the light will flash.

如果我們在沒有電容器的情況下快速接通和斷開一個簡單的電路，那麼燈就會閃爍。

But if we connect a capacitor into the circuit, then the light will remain on during the interruptions, at least for a short duration, because the capacitor is now discharging and powering the circuit.

但是，如果我們在電路中接入一個電容器，那麼在中斷期間，至少在短時間內，電燈會一直亮著，因為電容器現在正在放電，併為電路供電。

Inside a basic capacitor, we have two conductive metal plates, which are typically made from aluminium or aluminium, and these will be separated by dielectric insulating material such as ceramic.

在基本電容器內部，我們有兩塊導電金屬板，通常由鋁或鋁製成，這兩塊金屬板之間由陶瓷等絕緣介質材料隔開。

Dielectric means the material will polarise when in contact with an electric field, and we'll see what that means shortly.

介電意味著材料在與電場接觸時會產生極化，我們很快就會知道這意味著什麼。

One side of the capacitor is connected to the positive side of the circuit and the other side is connected to the negative.

電容器的一側與電路的正極相連，另一側與負極相連。

On the side of the capacitor, you will see a stripe and a symbol.

在電容器的側面，您會看到一條條紋和一個符號。

This will indicate which side is the negative.

這將表明哪一邊是負極。

If we were to connect a capacitor to a battery, the voltage will push the electrons from the negative terminal over to the capacitor.

如果我們將電容器連接到電池上，電壓會將負極的電子推向電容器。

The electrons will build up on one plate of the capacitor, while the other plate in turn releases some electrons.

電子將積聚在電容器的一個板上，而另一個板則釋放出一些電子。

The electrons can't pass through the capacitor because of the insulating material.

由於絕緣材料的存在，電子無法通過電容器。

Eventually, the capacitor is the same voltage as the battery and no more electrons will flow.

最終，電容器的電壓與電池相同，不再有電子流動。

There is now a build-up of electrons on one side.

現在電子在一側聚集。

This means we have stored energy and we can release this when needed.

這意味著我們儲存了能量，在需要時可以釋放出來。

Because there are more electrons on one side compared to the other, and the electrons are negatively charged, this means we have one side which is negative and one side which is positive, so there is a difference in potential or a voltage difference between the two, and we can measure this with a multimeter.

由於一側的電子數量多於另一側，而且電子帶負電，這意味著一側為負，一側為正，是以兩者之間存在電位差或電壓差，我們可以用萬用表測量。

Voltage is like pressure.

電壓就像壓力。

When we measure pressure, we're measuring the difference or potential difference between two points.

測量壓力時，我們測量的是兩點之間的差值或電位差。

If you imagine a pressurised water pipe, we can see the pressure using a pressure gauge.

想象一下加壓的水管，我們可以通過壓力錶看到壓力。

The pressure gauge is comparing two different points also.

壓力錶也在比較兩個不同的點。

The pressure inside the pipe compared to the atmospheric pressure outside the pipe.

管道內壓力與管道外大氣壓力的比較。

When the tank is empty, the gauge reads zero because the pressure inside the tank is now equal to the pressure outside the tank, so the gauge has nothing to compare against.

當油箱是空的時候，壓力錶的讀數為零，因為此時油箱內的壓力等於油箱外的壓力，所以壓力錶沒有任何可比性。

Both are the same pressure.

兩者的壓力相同。

The same with voltage.

電壓也是如此。

We're comparing the difference between two points.

我們在比較兩點之間的差異。

If we measure across a 1.5 volt battery, then we read a difference of 1.5 volts between each end.

如果我們測量 1.5 伏電池兩端的電壓，則兩端的電壓差為 1.5 伏。

But if we measure the same end, then we read zero because there is no difference, it's going to be the same.

但如果我們測量的是同一端，那麼讀數就是零，因為沒有區別，讀數是一樣的。

Coming back to the capacitor, we measure across and read a voltage difference between the two because of the build-up of electrons.

回到電容器，由於電子的聚集，我們測量電容器兩端並讀取兩者之間的電壓差。

We still get this reading even when we disconnect the battery.

即使我們斷開電池連接，讀數依然如此。

If you remember with magnets, opposites attract and pull towards each other.

如果你還記得磁鐵的作用，那就是異性相吸，相互吸引。

The same occurs with the build-up of negatively charged electrons.

帶負電的電子的積累也是如此。

They are attracted to the positively charged particles of their atoms on the opposite plate.

它們被對面平板上帶正電荷的原子粒子所吸引。

They can never reach each other because of the insulating material.

由於絕緣材料的存在，它們永遠無法互相接觸。

This pull between the two sides is an electric field which holds the electrons in place until another path is made.

兩側之間的這種拉力就是一個電場，它將電子固定在原地，直到形成另一條路徑。

If we then place a small lamp into the circuit, a path now exists for the electrons to flow and reach the opposite side.

如果我們將一盞小燈接入電路，電子就有了一條通路，可以流向另一端。

So the electrons will flow through the lamp powering it and the electrons will reach the other side of the capacitor.

是以，電子將流過為其供電的燈管，電子將到達電容器的另一端。

This will only last a short duration though until the build-up of electrons equalises on each side.

但這種情況只會持續很短的時間，直到兩邊的電子積聚達到平衡。

Then the voltage is zero, so there is no pushing force and no electrons will flow.

這時電壓為零，是以沒有推動力，電子也不會流動。

Once we connect the battery again, the capacitor will begin to charge.

一旦我們再次連接電池，電容器就會開始充電。

This allows us to interrupt the power supply and the capacitor will provide power during these interruptions.

這樣，我們就可以中斷電源，電容器將在中斷期間提供電力。

So where do we use capacitors?

那麼，我們在哪裡使用電容器呢？

They look a little bit different but they are easy to spot.

它們看起來有些不同，但很容易發現。

In circuit boards they tend to look something like this.

在電路板中，它們往往看起來像這樣。

And we see them represented in engineering drawings with symbols like these.

我們可以在工程圖紙中看到這些符號。

We can also get larger capacitors which are used for example on induction motors, ceiling fans and air conditioning units.

我們還可以提供更大的電容器，例如用於感應電機、吊扇和空調設備的電容器。

We can get even larger ones which are used to create poor power factor in large buildings.

我們還能買到更大的，用於在大型建築物中產生較差的功率因數。

On the side of the capacitor we will find two values.

在電容器的側面，我們會發現兩個數值。

These are the capacitance and the voltage.

這就是電容和電壓。

We measure capacitance of the capacitor in the unit of farads which we show with a capital F, although we will usually measure a capacitor in microfarads.

我們測量電容器的電容時使用的組織、部門是法拉（farads），用大寫字母 "F "表示，但通常我們測量電容器時使用的組織、部門是微法拉（microfarads）。

With microfarads we just have a symbol before this which looks something like a letter U with a tail.

對於微法拉，我們只需在前面加上一個符號，看起來就像一個帶尾巴的字母 U。

The other value is our voltage which we measure in volts with a capital V.

另一個值是我們的電壓，測量組織、部門為伏特，大寫字母為 V。

On the capacitor the voltage value is the maximum voltage which the capacitor can handle.

電容器上的電壓值是電容器能承受的最大電壓。

We have covered voltage in detail in a separate video, do check that out, link is down below.

我們在另一個視頻中詳細介紹了電壓問題，請點擊下面的鏈接查看。

As I said the capacitor is rated to handle a certain voltage.

正如我所說，電容器的額定電壓是一定的。

If we were to exceed this then the capacitor will explode.

如果超過這個值，電容器就會爆炸。

Let's have a look at that in slow motion.

讓我們來看看慢動作。

Ah, pretty cool.

啊，太酷了

So why do we use capacitors?

那麼，我們為什麼要使用電容器呢？

One of the most common applications of capacitors in large buildings is for power factor correction.

電容器在大型建築中最常見的應用之一是功率因數校正。

When too many inductive loads are placed into a circuit the current and the voltage waveforms will fall out of sync with each other and the current will lag behind the voltage.

如果電路中的電感負載過多，電流和電壓波形就會不同步，電流就會落後於電壓。

We then use capacitor banks to counteract this and bring the two back into alignment.

然後，我們使用電容器組來抵消這種情況，使兩者恢復一致。

We've covered power factor before in great detail, do check that out, link is down below.

我們曾經詳細介紹過功率因數，請查看下面的鏈接。

Another very common application is to smooth out peaks when converting AC to DC power.

另一種非常常見的應用是在將交流電轉換為直流電時平滑峰值。

When we use a full bridge rectifier the AC sine wave is flipped to make the negative cycle flow in a positive direction.

當我們使用全橋整流器時，交流正弦波會翻轉，使負循環流向正方向。

This will trick the circuit into thinking it's getting direct current, but one of the problems with this method is the gaps in between the peaks.

這將欺騙電路，讓它以為得到的是直流電，但這種方法的問題之一是峰值之間存在間隙。

But as we saw earlier, we can use the capacitor to release energy into the circuit during these interruptions and that will smooth the power supply out to look more like a DC supply.

但正如我們之前看到的，我們可以利用電容器在這些中斷期間向電路釋放能量，這樣就能使電源看起來更像直流電源。

We can measure the capacitance and the stored voltage using a multimeter.

我們可以使用萬用表測量電容和存儲電壓。

Not all multimeters have the capacitance function, but I'll leave a link down below for the You should be very careful with capacitors, as we now know they store energy and can hold high voltage values for a long time even when disconnected from a circuit.

不是所有的萬用表都有電容功能，但我會在下面為您提供一個鏈接。 我們現在知道，電容器可以儲存能量，即使與電路斷開連接，也能長時間保持高電壓值，是以使用電容器時要非常小心。

To check the voltage we switch to DC voltage on our meter and then we connect the red wire to the positive side of the capacitor and the black wire to the negative side.

要檢查電壓，我們先將電流表切換到直流電壓，然後將紅線連接到電容器的正極，黑線連接到負極。

If we get a reading of several volts or more then we should discharge that by safely connecting the terminals to a resistor and continue to read the voltage.

如果讀取到幾伏或更高的電壓，我們就應該將端子安全地連接到電阻器上進行放電，然後繼續讀取電壓。

We want to make sure that it's reduced down into the millivolts range before handling it else we might get a shock.

我們要確保在處理它之前，它已經降到毫伏範圍內，否則我們可能會受到衝擊。

To measure the capacitance we simply switch the meter to the capacitor function.

要測量電容，我們只需將儀表切換到電容功能。

We connect the red wire to the positive side and the black wire to the negative side.

紅線連接正極，黑線連接負極。

After a short delay the meter will give us a reading.

稍作延遲後，儀表就會給出讀數。

We will probably get a reading close to the stated value but not exact.

我們可能會得到一個接近標稱值的讀數，但並不精確。

For example this one is rated at 1000 microfarads, but when we read it we get a measurement of around 946.

例如，這個額定值為 1000 微法爾德，但當我們讀取它時，得到的測量值約為 946。

This one is rated at 33 microfarads, but when we measure it we get around 36.

這個的額定值是 33 微法，但我們測量時得到的是 36 左右。

Ok guys that's it for this video but to continue your learning then check out one of the videos on screen now and I'll catch you there for the next lesson.

好了，夥計們，本期視頻就到這裡，如果想繼續學習，請查看螢幕上的視頻，我將在下一堂課中為大家介紹。

Don't forget to follow us on Facebook, Twitter, Instagram and of course TheEngineeringMindset.com

別忘了在 Facebook、Twitter、Instagram 和 TheEngineeringMindset.com 上關注我們。