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What is a Capacitor?
- Shy Swartz
- Nov 27, 2024
- 6 min read
Updated: Nov 28, 2024
So What Exactly is a Capacitor?
In electronics, a capacitor is a component that stores electrical energy, very similar to a battery. How ever unlike a battery, capacitors do not use a chemical reaction to store energy, they can not store as Much energy, and it takes them substantial less time to charge and discharge energy. Making them one of the most common, and useful components found in most circuits.
What is Inside of a Capacitor?
Located on the outside of every capacitor is two terminals, if the capacitor is polarized then there will be a stripe with minus signs or sometime a band of plus signs that runs the length of the capacitors body, corresponding to one of the legs, this indicates the orientation of the capacitor in the circuit, this is very important to Match correctly. If there is no plus or minus signs present on the capacitor then it is a non-polarized capacitors, or the orientation of the capacitor in circuit dose not matter.
Internally the two terminals are connected to two metal plates, normally aluminum. Sandwiched between the two plates is a substance called dielectric, which is simply a non conductive substance to ensure the two plates remain isolated. Some of the most common types of dielectric found inside of capacitors include ceramic, mica, porcelain, air, glass and
Teflon.
What are Capacitors Used For?
Capacitors have a wide range of uses including soothing out and stabilizing
voltage, timing and oscillation circuits, voltage regulation, coupling and decoupling circuits, starting and running moters and many more!
How do Capacitors Work?
a very easy way to visualize how a capacitor works is with a simple fence and gate diagram. below is a photo of a fence with cows inside.
the cows can move through the fence freely one by one at a constant rate.
When the farmer shuts the gate the cows come to a hault and the constant flow stops. The farmer wants to create a system that allows him to shut the gate without affecting the steady flow of cows.
The farmer installs a large waiting pen for the cows to gather in.
With this new waiting pen installed, the farmer can now shut the gate without affecting the steady flow of cows.
As long as the number of cows in the waiting pen never reaches zero there will be no affect to the steady flow of cows. There by allowing the farmer to open and close the gate as much as he wants without affecting the flow.
In the example above the waiting pen is acting like a capacitor. when the cows enter the waiting pen this is the equivalent to charging a capacitor. when the gate is shut the cows in the waiting pen will continue to move at a steady rate causing no interruptions to the flow, this repreisence the capacitor discharging. Now that we know how capacitors work lets look at a real life example of a capacitor in a circuit.
When we connect a battery to a LED the LED will light up.
When we remove the battery from the LED the LED will no longer light up.
If we install a capacitor in between the battery and the LED the battery will begin
to charge the capacitor while also lighting the LED.
Now if we remove the battery the LED will stay lit for a period of time because it is using the stored energy from the capacitor to power the LED.
As long as the battery is reconnected before the amount of electrons becomes equal on both sides of the capacitor the light will never turn off.
What are the markings on a capacitor?
Located on the side of every capacitor is two numbers, The capacitance of the capacitor and the voltage rating. These two number are easily distinguishable, the capacitance number is followed by the letters UF, UF meaning micro facades or the unit used to measure capacitance. The voltage rating number is simply followed by the letter V representing volts.
Sometimes you will also see a band of minus or plus signs that run the length of the capacitor. This means that the capacitor is polarized, or the orientation of the capacitor in circuit matters. In the photo you can see there is a band of minus signs that runs the length of the body of the capacitor, this indicates that leg of the capacitor that corresponds to the band is the negative leg of the capacitor, you will also see the the negative leg of the capacitor is shorter than the other one, this can also be a indicator of the cap being polarized.
What dose a capacitor look like on a schematic?
There many different types of capacitors and therefore many different types of schematic symbols for the different types. The two most common types of capacitor you will see in a circuit are polarized and non polarized below are the schematic symbols for both.
Lets see what you have learned!
Below is a short quiz to test how well you have comprehended the information about capacitors in this article. Your can vote on which answer you belive to be correct by simply clicking on the answer.
What type of capacitor is this?
Polarized
Non-Polarized
Answer: Non-Polerized
The capacitor shows two flat lines with no plus of minus signs, this make the capacitor non- polarized
What is the capacitance of this capacitor?
.001 UF
i don't know
Answer: .001 UF
On schematics it is very common for the capacitors in general to lack the "UF" symbol, so it is up to the reader to know that the number listed above the capacitor symbol is referencing capacitance.
What is the material that is sandwiched in between the two metal plates of a capacitor called?
Foil
Dielectric
Answer: Dielectric
Sandwiched between the two plates is a substance called dielectric, which is simply a non conductive substance to ensure the two plates remain isolated
If the battery is removed from this circuit will the light remain on?
Yes the light will stay on
No the light will turn off
Answer: Yes the light will stay on
If the battery is removed, the LED will use the stored energy from the capacitor to light the LED.
When the farmer opens the gate to the waiting pen what dose this represent?
The discharging of a capacitor
The charging of the capacitor
Answer: The charging of the capaciotr
when the cows enter the waiting pen this is the equivalent to charging a capacitor. when the gate is shut the cows in the waiting pen will continue to move at a steady rate causing no interruptions to the flow, this repreisence the capacitor discharging.
what is this number on the side of the capacitor?
The capacitance
The voltage rating
Answer: The capacitance
the capacitance number is followed by the letters UF, UF meaning micro facades or the unit used to measure capacitance.
What type of capacitor is this?
Polarized
Non-Polarized
Answer: Polarized
there is a minus and plus sign present on the schematic which indicates that the orientation of the capacitor matters in circuit, making it polarized
What dose this band tell you about this capacitor?
It tells you the voltage of the capacitor
It tells you that the capacitor is polarized
Answer: It tells you that the capacitor is polarized
When a capacitor is polarized then there will be a stripe with minus signs or sometime a band of plus signs that runs the length of the capacitors body, corresponding to one of the legs, this indicates the orientation of the capacitor in the circuit.
When the farmer closes the gate to the waiting pen what dose this represent?
The discharging of the capacitor
The charging of the capacitor
Answer: The discharging of the capacitor
when the gate is shut the cows in the waiting pen will continue to move at a steady rate causing no interruptions to the flow, this repreisence the capacitor discharging.
What is a common material used for dielectric in capacitor's ?
Argon
Oxygen
Answer: Oxygen
Some of the most common types of dielectric found inside of capacitors include ceramic, mica, porcelain, air, glass and
Teflon.
What is this number on the side of the capacitor?
The capacitance
The voltage rating
Answer: The voltage rating
The voltage rating number is easily identified by a number followed by the letter V, representing volts.
Which set of these schematic symbols indicates that the capacitor is polarized?
The set on the left is polarized
The set on the right is polarized
Answer: The set on the left is polarized
The set on the left is polarized due to the presents of a plus sign
Lets Recap
A capacitor is a component that stores electrical energy, very similar to a battery. How ever unlike a battery, capacitors do not use a chemical reaction to store energy, they can not store as Much energy, and it takes them substantial less time to charge and discharge energy.
Capacitors have a wide range of uses including soothing out and stabilizing
voltage, timing and oscillation circuits, voltage regulation, coupling and decoupling circuits, starting and running moters and many more!
Capacitors work by gaining a charge when a voltage is applied, when the voltage is removed capacitors will discharge the stored energy.
Located on the side of every capacitor is two numbers, The capacitance of the capacitor and the voltage rating. These two number are easily distinguishable, the capacitance number is followed by the letters UF, UF meaning micro facades or the unit used to measure capacitance. The voltage rating number is simply followed by the letter V representing volts.
Sometimes you will also see a band of minus or plus signs that run the length of the capacitor. This means that the capacitor is polarized, or the orientation of the capacitor in circuit matters.
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