Capacitors Explained - The basics how capacitors work working principle

Summary

In this video by Paul from TheEngineeringMindset.com, the functioning of capacitors is explained. Capacitors store electric charge, similar to batteries, but can charge and discharge energy much faster. Paul uses analogies, like comparing capacitors to water tanks, to illustrate how they smooth out power interruptions in circuits. He also discusses the components inside capacitors, their uses in various devices, and safety measures for handling them. The video includes practical examples, demonstrations of voltage and capacitance measurements, and highlights the importance of capacitors in circuits like power factor correction.

Takeaways

• ⚡ Capacitors store electric charge, similar to batteries, but release energy faster.
• 💡 Capacitors smooth out interruptions in electrical circuits by releasing stored energy when needed.
• 🔌 Inside a capacitor, two conductive plates are separated by a dielectric insulating material that polarizes in an electric field.
• 🔋 When connected to a battery, capacitors store energy by building up electrons on one plate while the other releases some electrons.
• 🧲 The buildup of electrons creates a voltage difference across the capacitor, which can be measured even when the power source is disconnected.
• 🔍 Capacitors are used in various applications, such as in circuit boards, induction motors, ceiling fans, and large buildings for power factor correction.
• ⚙ Capacitors help correct poor power factor by bringing voltage and current waveforms back into sync in circuits with many inductive loads.
• 🔄 Capacitors smooth out gaps in AC-to-DC conversion by releasing energy during interruptions in the waveform.
• 📏 Capacitors are measured in Farads (F), with microfarads (µF) being common, and voltage ratings indicate the maximum voltage they can handle.
• ⚠ Capacitors can hold high voltage for long periods, so care must be taken to discharge them safely before handling to avoid electric shock.

Q & A

What is a capacitor and how is it different from a battery?

A capacitor is a device that stores electrical charge. Unlike a battery, which stores energy chemically, a capacitor stores it in an electric field. Capacitors can charge and discharge energy much faster than batteries but cannot store as much energy.

How does a capacitor work in an electrical circuit?

A capacitor works by storing charge on two metal plates separated by an insulating material. When connected to a power source, electrons build up on one plate, creating a difference in potential (voltage). This stored energy can then be released when needed, like during power interruptions.

What analogy is used to explain how a capacitor works?

The video uses a water tank analogy. The water flowing through a pipe represents the electric current, and the tank represents the capacitor. Just as a tank stores water and smooths out interruptions in water flow, a capacitor stores electrical charge and smooths out interruptions in power supply.

What materials are typically used to make the plates and insulating layer in a capacitor?

The plates in a capacitor are typically made of conductive metals like aluminum, while the insulating layer (dielectric) is often made of ceramic or other dielectric materials that polarize when exposed to an electric field.

What is the function of a dielectric material in a capacitor?

The dielectric material in a capacitor acts as an insulator, preventing electrons from passing between the two plates. It also polarizes when exposed to an electric field, helping the capacitor store energy more effectively.

How does a capacitor smooth out power interruptions in a circuit?

When a power supply is interrupted, the capacitor discharges its stored energy, providing power to the circuit for a short duration. This prevents devices like lights from flickering during the interruptions.

What happens if a capacitor is exposed to a higher voltage than its rated capacity?

If a capacitor is exposed to a voltage higher than its rated capacity, it can explode. The video even demonstrates this happening in slow motion.

What are some common applications of capacitors?

Capacitors are commonly used in circuit boards, induction motors, ceiling fans, air conditioning units, and for power factor correction in large buildings. They are also used to smooth out peaks when converting AC to DC power.

What are the two main values found on a capacitor, and what do they represent?

The two main values on a capacitor are capacitance and voltage. Capacitance, measured in Farads (usually microfarads), represents the capacitor's ability to store charge, while voltage represents the maximum voltage the capacitor can safely handle.

How do you safely discharge a capacitor before handling it?

To safely discharge a capacitor, you connect its terminals to a resistor and monitor the voltage using a multimeter. You should continue discharging until the voltage is in the millivolt range to avoid electric shock.

Outlines

00:00

⚡️ Introduction to Capacitors and Their Importance

In this opening paragraph, Paul from TheEngineeringMindset.com introduces the concept of capacitors. He emphasizes the dangers of electricity, warning viewers to avoid touching capacitor terminals due to potential electric shocks. Capacitors are introduced as devices that store electric charge, similar to batteries but faster in energy release. Paul outlines that capacitors are essential in nearly every circuit board because of their ability to store and discharge energy rapidly.

05:02

🚰 Water Analogy for Capacitor Function

Paul uses a water pipe analogy to explain how capacitors work. He likens a capacitor to a water tank that stores water (energy) when a valve is closed and releases it smoothly, avoiding interruptions in the flow. Similarly, capacitors store and release energy to smooth out interruptions in an electrical circuit. Without a capacitor, a light might flash on and off, but with one, the light stays on briefly during power interruptions, showing how capacitors can stabilize electrical flow.

🔋 Basic Components and Structure of a Capacitor

Here, Paul breaks down the internal structure of a basic capacitor, which consists of two metal plates separated by an insulating material known as a dielectric. He explains how the capacitor is connected to a circuit, how electrons build up on one plate when a voltage is applied, and how this creates a stored charge. The key takeaway is that the insulating material prevents the electrons from moving directly between plates, allowing the capacitor to store energy until it’s discharged.

📐 Measuring Voltage and Understanding Electric Fields

Paul goes deeper into the science of capacitors, explaining how voltage works by comparing it to pressure in a water pipe. He explains that voltage is the potential difference between two points, similar to how pressure gauges compare pressure inside a pipe with the atmospheric pressure outside. In a charged capacitor, the voltage difference comes from the build-up of electrons on one side. This creates an electric field, holding the electrons in place until a circuit path allows them to flow.

💡 Discharging a Capacitor to Power a Circuit

In this section, Paul demonstrates how a charged capacitor can power a circuit temporarily. When the capacitor is connected to a small lamp, the electrons flow from one side to the other, powering the lamp until the charge is balanced and the voltage drops to zero. He emphasizes that once the charge is used up, no more electrons flow until the capacitor is recharged by reconnecting it to a power source.

🛠 Common Uses of Capacitors in Circuits

Paul shifts focus to practical applications of capacitors, explaining where they are commonly used. Capacitors are found in a variety of devices, from small circuit boards to large induction motors and air conditioning units. They are also used for power factor correction in large buildings, ensuring that the current and voltage waveforms remain synchronized. He discusses how capacitors help smooth out power fluctuations, especially when converting AC to DC power.

🔧 Measuring Capacitance and Voltage Safely

In this final technical section, Paul provides a step-by-step guide on how to measure the capacitance and voltage of a capacitor using a multimeter. He stresses the importance of safety when handling capacitors, as they can retain charge even after being disconnected from a circuit. He explains how to safely discharge a capacitor using a resistor and how to take accurate readings of both capacitance and voltage.

📊 Conclusion and Additional Learning Resources

Paul wraps up the video by encouraging viewers to continue learning about capacitors and related electrical concepts. He provides links to other videos for further study and promotes the channel's social media platforms. He ends by reminding viewers of the importance of safety when working with electrical components like capacitors.

Keywords

💡Capacitor

A capacitor is a device that stores electrical energy, similar to a battery but with distinct differences. It can charge and release energy much faster than a battery, which makes it useful in almost every circuit. Capacitors store energy between two conductive plates separated by an insulating material, and this energy can be released to smooth out power supply interruptions, as described when the light stays on despite the circuit being turned on and off.

💡Dielectric

A dielectric is an insulating material placed between the plates of a capacitor. Its role is to prevent the flow of electricity while allowing the build-up of an electric field. When exposed to an electric field, the dielectric becomes polarized, meaning it holds energy without allowing electrons to pass through. The script explains this using ceramic as an example of a dielectric material in capacitors.

💡Electric field

An electric field refers to the force exerted by charged particles. In the case of capacitors, the buildup of electrons on one plate creates a negative charge, which is attracted to the positive charge on the opposite plate, generating an electric field between them. This field holds the electrons in place, storing energy until a path is created for them to move, like when a lamp is connected to the circuit.

💡Voltage

Voltage is the measure of potential difference between two points in an electric circuit. It is likened to pressure in a water pipe in the video. In capacitors, voltage represents the difference between the number of electrons on each plate. The capacitor charges until its voltage equals that of the battery, and when measured, this difference shows the stored energy within the capacitor.

💡Microfarads

Microfarads (µF) are units used to measure a capacitor's capacitance, which indicates how much electric charge it can store. Farads are the base unit, but most capacitors have values in microfarads since their capacitance is relatively small. The video demonstrates this with examples, showing a capacitor rated at 1,000 µF being measured at 946 µF, and a 33 µF capacitor measuring at 36 µF.

💡Power factor correction

Power factor correction is a technique used in large buildings to balance the voltage and current waveforms, which can fall out of sync due to inductive loads. Capacitors are often used to correct this issue by realigning the two waveforms. The video discusses how capacitor banks are employed in buildings to improve power factor, ensuring efficient energy use.

💡Rectifier

A rectifier is a device that converts alternating current (AC) to direct current (DC). The script explains that a full bridge rectifier flips the AC sine wave so that both halves flow in a positive direction, mimicking a DC current. However, gaps appear between the peaks, and capacitors are used to smooth out these interruptions by releasing stored energy during the gaps.

💡Inductive load

Inductive loads are electrical components, like motors or transformers, that cause the current to lag behind the voltage in a circuit. This can result in inefficiencies, and the video explains that capacitors help correct the phase difference, bringing the current and voltage back into alignment, particularly in large buildings where many inductive loads are used.

💡Multimeter

A multimeter is a tool used to measure various electrical properties, including voltage, capacitance, and resistance. In the video, the multimeter is used to measure the voltage across a capacitor and its capacitance, ensuring the capacitor is functioning properly. It also helps ensure safety by measuring whether a capacitor has been fully discharged before handling.

💡Capacitance

Capacitance is the ability of a capacitor to store an electric charge, measured in farads. It reflects how much electric energy the capacitor can hold relative to the voltage applied. The video demonstrates measuring capacitance using a multimeter, showing how real-world capacitance values might differ slightly from the stated values on the capacitor.

Highlights

Introduction to capacitors and their importance in electrical circuits.

Capacitors store electric charge and release it faster than batteries.

Capacitors smooth out interruptions in electrical circuits, ensuring uninterrupted power.

Comparison of a capacitor's function to a water tank storing water to prevent interruptions in flow.

Basic structure of a capacitor includes two conductive metal plates separated by a dielectric material.

Capacitors store energy by building up electrons on one plate, creating a voltage difference between the plates.

Explanation of how the electric field inside a capacitor holds electrons in place.

Capacitors release stored energy when the circuit needs it, keeping the system running smoothly during interruptions.

Capacitors are commonly used in circuit boards, induction motors, ceiling fans, and air conditioning units.

Capacitors are measured in Farads, typically microfarads, with a maximum voltage rating.

Exceeding a capacitor's voltage rating can result in it exploding, as shown in slow-motion footage.

Capacitors are used in large buildings for power factor correction, aligning current and voltage waveforms.

Capacitors smooth out power supply in AC-to-DC conversions, filling gaps between peaks in waveforms.

Capacitors can hold high voltage even when disconnected from circuits, requiring careful handling.

Practical demonstration of using a multimeter to measure voltage and capacitance of capacitors.

Transcripts

Hey, there, guys.

Paul here from TheEngineeringMindset.com.

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.

Remember, electricity is dangerous and can be fatal.

You should be qualified and competent

to carry out any electrical work.

Do not touch the terminals of a capacitor,

as it can cause an electric shock.

So, what is a capacitor?

A capacitor stores electric charge.

It's a little bit like a battery,

except it stores energy in a different way.

It can't store as much energy as a battery,

although it can charge and release its energy much faster.

This is very useful, and that's why you will find capacitors

used in almost every circuit board.

So, how does the capacitor work?

I want you to first think of a water pipe

with water flowing through it.

The water will continue to flow until we shut the valve,

then no water can flow, 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.

Now when we close the valve,

water will stop pouring into the tank

but we still get the steady supply

of water out until the tank empties.

Once the tank is filled again,

we can open and close the valve as many times as we like.

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.

So, we can use a water tank to store water

and smooth out interruptions to the supply.

In electrical circuits, the capacitor acts as the water tank

and stores energy.

It can release this to smooth out interruptions

to the supply.

If we turned a simple circuit on and off very fast

without a capacitor, then the light will flash,

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.

Inside a basic capacitor,

we have two conductive metal plates,

which are typically made from aluminium or aluminum,

and these will be separated

by a dielectric insulating materials such as ceramic.

Dielectric means the material will polarize

when in contact with an electric field,

and we'll see what that means shortly.

One side of the capacitor is connected

to the positive side of the circuit,

and the other side is connected to the negative.

On the side of the capacitor,

you will see a stripe and a symbol.

This will indicate which side is the negative.

If we were to connect a capacitor to a battery,

the voltage will push the electrons

from the negative terminal over to the capacitor.

The electrons will build up on one plate of the capacitor,

while the other plate, in turn, releases some electrons.

The electrons can't pass through the capacitor

because of the insulating material.

Eventually, the capacitor is the same voltage as the battery

and no more electrons will flow.

There is now a buildup of electrons on one side.

This means we have stored energy

and we can release this when needed.

Because there are more electrons on one side compared

to the other, and 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.

Voltage is like pressure.

When we measure pressure, we're measuring the difference

or potential difference between two points.

If you imagine a pressurized water pipe,

we can see the pressure using a pressure gauge.

The pressure gauge is comparing two different points, also:

the pressure inside the pipe compared

to the atmospheric pressure outside the pipe.

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;

both are the same pressure.

The same with voltage, we're comparing the difference

between two points.

If we measure across a 1.5 volt battery,

then we read a difference of 1.5 volts between each end,

but if we measure the same end, then we read zero

because there's no difference and it's going to be the same.

Coming back to the capacitor, we measure across

and read a voltage difference between the two

because of the buildup of electrons.

We still get this reading

even when we disconnect the battery.

If you remember, with magnets,

opposites attract and pull towards each other.

The same occurs with the build-up

of negatively charged electrons.

They are attracted to the positively charged particles

of their atoms on the opposite plate.

They can never reach each other

because of the insulating material.

This pull between the two sides is an electric field,

which holds electrons in place until another path is made.

If we then place a small lamp into the circuit,

a path now exists for the electrons to flow

and reach the opposite side.

So, the electrons will flow through the lamp, powering it,

and the electrons will reach the other side

of the capacitor.

This will only last a short duration, though,

until the buildup of electrons equalizes on each side.

Then the voltage is zero.

So, there is no pushing force and no electrons will flow.

Once we connect the battery again,

the capacitor will begin to charge.

This allows us to interrupt the power supply

and the capacitor that will provide power

during these interruptions.

So, where do we use capacitors?

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

In circuit boards, they tend to look something like this,

and we see them represented in engineering drawings

with symbols like these.

We can also get larger capacitors,

which are used, for example, on induction motors,

ceiling fans, and air conditioning units.

We can get even larger ones,

which are used to correct poor power factor

in large buildings.

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

These are the capacitance and the voltage.

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.

With microfarads, we just have a symbol before this,

which looks something like a letter U with a tail.

The other value is our voltage,

which we measure in volts, with a capital V.

On the capacitor, the voltage value is the maximum voltage

which the capacitor can handle.

We've covered voltage in detail in a separate video.

Do check that out, link's down below.

As I said, the capacitor is rated

to handle a certain voltage.

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

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

Eh, pretty cool.

So, why do we use capacitors?

One of the most common applications of capacitors

in large buildings is for power factor correction.

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.

We then use capacitor banks to counteract this

and bring the two back into alignment.

We've covered power factor before in great detail.

Do check that out, link's down below.

Another very common application is to smooth out peaks

when converting AC to DC power.

When we use a full bridge rectifier,

the AC sine wave is flipped

to make the negative cycle flow in a positive direction.

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.

But as we saw earlier, we can use a 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.

We can measure the capacitance

and the stored voltage using a multimeter.

Not all multimeters have the capacitance function,

but I'll leave a link down below

for the model which I personally use.

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.

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.

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.

We want to make sure that it's reduced down

into the millivolts range before handling it,

or else we might get a shock.

To measure the capacitance, we simply switch the meter

to the capacitor function.

We connect the red wire to the positive side

and the black wire to the negative side.

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

We will probably get a reading close to the stated value

but not exact.

For example, this one is rated at 1,000 microfarads,

but when we read it, we get a measurement of around 946.

This one is rated at 33 microfarads,

but we measure it, we get around 36.

Okay, 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.

Don't forget to follow us on Facebook, Twitter, Instagram,

and of course, TheEngineeringMindset.com.