Capacitor, Capacitance, charge time, and Charge Explained

A capacitor is a passive two-terminal electronic component used to store energy electrostatically in an electric field.

The form of practical capacitors varies greatly, but all contain at least two electrical conductors (plates) separated by a dielectric.

The conductor can be a thin film such as metal, aluminum foil, or disc. The role of the “non-conductive” dielectric is to increase the charging capacity of the capacitor.

ceramic and Electrlytic Capacitor
ceramic and Electrlytic Capacitor

The dielectric can be glass, ceramic, plastic film, air, paper, mica, etc. Capacitors are widely used as part of circuits in much common electrical equipment.

Unlike resistors, capacitors do not dissipate energy. Instead, capacitors store energy in the form of an electrostatic field between their plates.

When there is a potential difference between conductors, an electric field is generated on the dielectric, so that positive charges (+ Q) are collected on one plate, and negative charges (-Q) are collected on one plate.

Collect the plate on another plate. If the battery has been connected to the capacitor long enough, no current can flow through the capacitor.

However, if acceleration or AC voltage is applied between the leads of the capacitor, displacement current will flow.

An ideal capacitor is characterized by a single constant value of its capacitance. Capacitance is expressed as the ratio of the charge (Q) on each conductor to the potential difference (V) between them.

The SI unit of capacitance is Farad (F), which is equal to one coulomb/volt (1 C/V). Typical capacitance values ​​range from about 1 pF (10-12 F) to about 1 mF (10-3 F).

When the spacing between the conductors is narrow, and when the surface area of ​​the conductor is larger, the capacitance will be greater. In fact, the dielectric between the plates will flow a small amount of leakage current, and it also has an electric field strength limit (called breakdown voltage). Conductors and wires introduce undesirable inductance and resistance.

Capacitors are widely used in electronic circuits to block direct current while allowing alternating current to pass through.

In the analog filter network, they can smooth the power output. In resonant circuits, they tune the radio to a specific frequency. In power transmission systems, they stabilize voltage and power flow.

Capacitance of a Capacitor

Capacitance is the electrical property of a capacitor. It is a measure of the ability of a capacitor to store charge on its two plates.

Its capacitance unit is Faraday (abbreviated as F), named after British physicist Michael Faraday.

Capacitance is defined as when a Coulomb charge is stored on the board at a voltage of one volt, the capacitor has a Farad capacitance.

Please note that the capacitance C is always positive and there is no negative unit. However, Farad is a very large unit of measurement and cannot be used alone.

Therefore, it is usually a multiple of Farad, such as micro Farad, nano Farad, and picofarad.

Units of Capacitance

  •   μF   1μF = 1/1,000,000 = 0.000001 = 10-6 F
  •   nF   1nF = 1/1,000,000,000 = 0.000000001 = 10-9 F
  •  pF  1pF = 1/1,000,000,000,000 = 0.000000000001 = 10-12 F


  • Microfarad  = μF
  • Nanofarad = nF
  • Picofarad  = pF
  • What is the SI unit of the capacitor: The SI unit of capacitance is the farad (symbol: F), named after British physicist Michael Faraday. When a 1-farad capacitor is charged with 1 coulomb of charge, the potential difference between its plates is 1 volt. The reciprocal of capacitance is called elasticity.

Capacitance of a Parallel Plate Capacitor

Capacitance is the amounts of charges stored per voltages. The unit of capacitance is Faraday (F), named after Faraday (1791-1867).

He is a British scientist in the field of electromagnetics and electrochemistry. Since capacitance is the charge per unit voltage, we can see that Farads are coulombs per volt.

The parallel plate capacitor shown in Figure 4 has two identical conductive plates, each of which has a surface area A, and the distance between them is d.

when a voltage V is applied to the capacitor, it stores charge Q. By considering the characteristics of the Coulomb force, we can see how its capacitance depends on A and d.

We know that repulsion is like an electric charge. Unlike electric attraction, the force between electric charges decreases with distance.

Therefore, the larger the plates, the more charge they can store, which seems reasonable because the charge can diffuse more. Therefore, for the larger A, C should be larger.

Similarly, the closer the distance between the plates, the greater the attraction of opposite charges to them. Therefore, for smaller d, C should be larger.

capacitor charge

Sometimes it is easier to remember this relationship by using pictures. Here, three quantities of Q, C, and V are superimposed into a triangle, giving charge at the top and capacitance and voltage at the bottom.

This arrangement represents the actual location of each quantity in the capacitor charge formula.

Then from the top, we can define the unit of capacitance as a constant of proportionality equal to Coulomb/volt, also known as the farad unit F.

Since capacitance represents the capacity (capacity) of a to store charge on its plates, we can define a farad is the capacitance of a capacitor that first needs a Coulomb charge to establish a potential difference of one volt between its plates.

capacitor charge Explaining figure
capacitor charge

Described by Michael Faraday. Therefore, the larger the capacitance, the higher the amount of charge stored on the capacitor for the same amount of voltage.

The ability of a capacitor to store charge on its conductive plate gives it a capacitance value.

The capacitance can also be determined based on the size or area of ​​the plates, A, and the properties of the dielectric material between the plates.

Also Read:- How Tօ Tеst A Capacitor

capacitor charge formula

The control formula for capacitor design is:- C = εA/ d, in this formula, C is capacitance; C is capacitance. ε is the dielectric constant, how well the dielectric material stores the electric field.

A is the area of ​​the parallel plates; d is the distance between the two conductive plates.

capacitor charge and discharge

This experiment requires a large-capacity capacitor to generate a sufficiently slow time constant to track using a voltmeter and stopwatch.

Please note that most large capacitors are of the “electrolytic” type and they are polarity sensitive! One terminal of each should be marked with a clear polarity symbol.

Generally, capacitors of a specified size have a minus sign (-) or a series of minus signs pointing to the negative terminal.

Very large capacitors usually have a positive sign (+) next to one terminal to mark the polarity.

Even if the power supply voltage is as low as 6 volts, failure to pay attention to the correct polarity will almost certainly cause the to malfunction.

When electrolytic capacitors fail, they usually explode, spray out corrosive chemicals and emit a foul smell. Please, please avoid this situation.

capacitor charge time

After 5 time constants, the capacitor will be charged to a level very close to the power supply voltage for all wide-ranging applications.

The capacitor will never be fully charged to the maximum voltage of its supply voltage, but it will be very close.

flux capacitor

Flux capacitor is a technology in the 1985 time travel movie Back to the Future and its subsequent works. Although it is described as the thing that makes time travel possible, its working principle has not been explained.

It consists of only a box with three flashing lights connected in a Y shape, installed in the iconic time wagon DeLorean in the movie.

This is a short-lived sports car known for its doors, which can be opened instead of Open outwards. The magnetic flux was invented by Doc Brown (Christopher Lloyd), which allowed Marty McFly (Michael J. Fox) to travel time.

The flux capacitor is an interesting sci-fi technology composed of two real scientific terms. In physics, magnetic flux refers to the amount of a certain object that passes through the surface of a given object, and a is a device that stores an electrical charge.

Some clever engineers nodded to the movie and built devices called flux capacitors, even though these real-life manufacturing has not yet reached the time difference.


What is a capacitor used for

A capacitor is a passive two-terminal electronic component used to store energy electrostatically in an electric field. Practical capacitors vary in various forms, but they all contain at least two electrical conductors (plates) separated by a dielectric

What is a capacitor and how does it work

A capacitor is an electrical component that can absorb and store energy from the battery. Inside, the terminals are connected to two metal plates separated by a non-conductive substance. After activation, the capacitor will quickly release electrical energy within a fraction of a second.

What is the working principle of a capacitor

The working principle of a capacitor is that when the grounding conductor is brought close to the conductor, the capacitance of the conductor will increase significantly. Therefore, a capacitor has two plates, which are separated by a certain distance and have equal and opposite charges.

Can a capacitor kill you

Capacitors are not deadly, they cannot kill you. The voltage stored in the capacitor and the current during discharge may harm you.The energy stored in a capacitor is proportional to the capacitance of the capacitor and the square of the terminal voltage.

Are capacitors DC or AC

Since direct current only flows in one direction, once the capacitor is fully charged, no current will flow anymore. …When the plates are discharged when the direction changes, the output current of the capacitor alternates with the AC voltage in phase. It is said that this is how the capacitor “passes” alternating current.

You Tube Video

So Here Is A YouTube Video Based On Capacaitor, Which Was Uploaded By The Engineering Mindset

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