Introduction
A capacitor is an electronic component, such as a small rechargeable battery, Capacitor can store energy or “capacity” in the form of an electric charge. however, this produces a potential difference (static voltage) across its plates.
What is Capacitor?
Capacitors are also called condenser. Capacitor is one of the passive components like resistor and inductor. The charge on the capacitor is stored in the form of an “electric charge”. Capacitors play an important role in many electrical and electronic circuits.
Capacitor symbol
Capacitor symbols are two types Base on the US standard capacitor and US standard capacitor for both polarized. Also, nonpolarized Capacitors
Working of capacitor
Capacitor consists of two conductors separated by a dielectric or insulating material when there is any potential difference between the two conductor’s (+ve and -ve) electric potential is arise. This causes the capacitor to charge and discharge.
Dielectric: when dielectrics are placed in an electric field, no current flows through them, which is because unlike metals they do not have loose bound or free electrons.
Potential difference: between two points that represents the work involved or the energy released in the transfer of a unit quantity of electricity from one point to the other.
In practical way: When the capacitor is connected to a battery current starts flowing through the circuit. However, negative charge is collected on one plate and positive charge is collected on the other plate. This process continuous until the capacitor voltage reaches supply voltage.
When the charging voltage is equal to the supply voltage capacitor stops charging. If there is no refilling current after capacitor charges fully, it will lose charge due to self-discharge.
In below circuit capacitor is connected to the power supply and the current flows through the circuit. However, Both the plates of the capacitor get the equal and opposite charges, that is +Q and -Q and the potential difference Vc start increasing while the capacitor is charging.
Once the voltage at the terminal of the capacitor (Vc) is equal to the power supply (V), that is (V=VC) Then capacitor stop charging.
Now connect the switch to position B. Now you can see the LED starts glowing and this slowly fades out as the capacitor is discharging
Capacitor Color Codes
Like resistors the color-coding system is also used in the capacitors. However, using this international color-coding system, the user can determine the value of capacitance of the capacitor including the tolerances. In this color-coding system, the color bands are used to determine the capacitance value. Table below shows the color bands to determine the value of the capacitor.
Standard Units of Capacitance
Farad (F): Farad (abbreviated as F) named after the British physicist Michael Faraday. However, Capacitance is the electrical property of a capacitor, and a unit of capacitance is the amount of capacity it can store an electric charge across two plates of capacitors. Capacitance is normally measured in some subunits such as micro farads (μF) or pico-farads (pF).
Most electronic/electrical applications include the following standard unit (SI) prefixes for easy calculations,
1 mF (millifarad) = 10−3 F = 1000 μF = 1000000 nF
1 μF (microfarad) =10−6 F = 1000 nF = 1000000 pF
1 nF (nanofarad) = 10−9 F = 1000 pF
1 pF (picofarad) = 10−12 F
The Capacitance of a Capacitor
A capacitance unit, it is a unit of capacity that holds an electric charge across two plates of capacitors, called the Farad (symbol: F) by the British physicist Michael Faraday. A 1 farad capacitor, when charged with 1 coulomb of electrical charge, has a potential difference of 1 volt between its plates.
Types of capacitors
Electrolytic Capacitors
Electrolytic capacitor is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodizing. This oxide layer acts as the dielectric of the capacitor.
Aluminum Electrolytic Capacitors
Aluminum electrolytic capacitors are polarized electrolytic capacitors. Moreover, the anode electrode (+) is made of pure aluminum foil.
Tantalum Electrolytic Capacitors
Capacitors made with tantalum can be either polar and non-polar though the polarized form is more common. However, Tantalum capacitors have higher capacitance per volume
Ceramic Capacitors
Ceramic capacitors are mainly used for high stability performances. At the same time, low-loss equipment. These devices give very accurate output. However, the capacitance values of these capacitors are constant with respect to the applied voltage, frequency, and temperature.
Variable Capacitor
A variable capacitor is a capacitor whose capacitance may be on purpose and repeatedly changed by mechanically or electronically. However, Variable capacitors are often used in L/C circuits to set the resonance frequency, Eg: to tune a radio.
Film Capacitor
Film capacitors are used for high frequency high power applications such as AC capacitors for power supply. The AC voltage ratings of these capacitors are up to 400 Kv. However, this capacitor is often used in Induction heating, pulsed power
Inside the capacitor
Electrolytic capacitors can be either solid polymer or wet-electrolyte. In addition, they are commonly made of tantalum or aluminum, although other materials may be used. However, electrolytic capacitor is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodizing. This oxide layer acts as the dielectric of the capacitor.
Capacitors in Series
Much like resistors are a pain to add in parallel, capacitors get funky when placed in series. The total capacitance of N capacitors in series is the inverse of the sum of all inverse capacitances. If you only have two capacitors in series. Therefore, you can use the “product-over-sum” method to calculate the total capacitance
Capacitors in Parallel
When capacitors are placed in parallel with one another the total capacitance is just the sum of all capacitance. This is like the way resistors add when in series.
Eg: if you had three capacitors of values 10µF, 1µF, and 0.1µF in parallel, the total capacitance would be 11.1µF (10+1+0.1).
Capacitive Voltage Divider
Capacitive voltage dividers consist of two capacitors. One of the capacitors is connected from the input to the output and the second one is connected from the output to ground.
The output voltage can be calculated with the following formula:
V in is the input voltage and is measured in volt (V)
C is the symbol for capacitance and is measured in farad (F).
V out is the output voltage and is measured in volt (V)
