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Complex circuits are made up of simple circuits. Simple circuits are made up of individual components.
You will be able to understand and remember what each component does if you learn about each component in the following three steps:
1 - How the component is created
2 - How the component behaves
3 - Examples of where the component is used
Capacitors
The original concept of the capacitor is the parallel plate capacitor.
In a science laboratory experiment, a parallel plate capacitor consists of two circular plates separated by some distance. The space between the plates can be any electrical insulating material, such as vacuum, air, paper, plastic, glass, etc.
The value of the capacitance increases with the size of the plates (area) and decreases with the distance separating the plates.
Reference: https://www.electronics-tutorials.ws/capacitor/cap_1.html
The formula for capacitance of a parallel plate capacitor is:
As can be seen in the formula, capacitance C increases linearly with the area A (i.e. directly proportional to area A) and decreases with the distance D between the plates (i.e. inversely proportional to distance D).
Electronic symbol of a capacitor
You will observe that the electronic symbol of a capacitor is very appropriately drawn as two lines with a gap between the two lines. From the information presented so far, you can make the observation that a capacitor is an open circuit. No direct current can flow between the plates of the capacitor. A resistance measurement with an ohmmeter will give a reading of infinite ohms.
Properties of Capacitors
One of the early experiments with capacitors is with one known as the Leyden Jar. This consisted of a glass jar lined with lead foil on the inside and outside to form the plates of the capacitor. Early experimenters would charge the capacitor using static electricity by rubbing an ebony rod with wool or a glass rod with a silk cloth. As the story is told, in Paris in 1746, Abbé Nolle charged a Leyden and discharged it on a line of monks holding hands. The monks all jumped simultaneously as the electric charge traveled through their bodies.
Capacitors store charge
From this we observe that capacitors store electric charge.
Can capacitors serve as batteries? Yes, they can. Physical capacitance values range from 1pF to 1F which is a range of 12 orders of magnitude, 10 raised to the power 12. Capacitors with very high capacitances are not easy to make. A parallel plate air-gapped capacitor of 1F would be astronomically large and next to impossible to make. However, with advanced materials in dielectric materials, 1000F capacitors and even higher are now readily manufactured (albeit at low voltages, 2.7V). For obvious reasons, these are called super capacitors.
Here is a bank of 3000F 2.7V individual capacitors.
An electronic photo flash requires a burst of energy at 300V in a short duration to excite the xenon flash lamp. One 1.5V AA battery cannot supply that energy continuously. However, since the photo flash is only needed once with a long resting period, a 160μF capacitor is charged to the required 300V from a single 1.5V battery.
Capacitors take time to charge and discharge
If you charge a capacitor with a constant current I, the voltage on the capacitor rises linearly with time.
Let us look at the math.
The amount of charge (Q coulombs) placed on the capacitor is current (I amps) multiplied by time (t seconds).
Q = I x t
The attained voltage V (volts) on the capacitor is a function of the capacitance C (farads) and the charge Q.
Q = C x V
Putting the two equations together, we get
Q = I x t = C x V
or
V = I x t / C
A large capacitor takes longer to charge than a smaller capacitor.
If we were to charge the capacitor from a constant voltage, the charging current decreases (as an inverse exponential) as the difference in voltage between the source voltage Vs and the capacitor voltage Vc gets smaller. The charging current gets smaller and smaller. In theory, the voltage Vc on the capacitor never fully reaches the charging voltage Vs.
The take away here is that we can apply this behaviour of a capacitor in applications that involve time, for example, time delays, pulse widths, frequency, duration, etc.
To be continued in Part 2.
Complex circuits are made up of simple circuits. Simple circuits are made up of individual components.
You will be able to understand and remember what each component does if you learn about each component in the following three steps:
1 - How the component is created
2 - How the component behaves
3 - Examples of where the component is used
Capacitors
The original concept of the capacitor is the parallel plate capacitor.
In a science laboratory experiment, a parallel plate capacitor consists of two circular plates separated by some distance. The space between the plates can be any electrical insulating material, such as vacuum, air, paper, plastic, glass, etc.
The value of the capacitance increases with the size of the plates (area) and decreases with the distance separating the plates.
Reference: https://www.electronics-tutorials.ws/capacitor/cap_1.html
The formula for capacitance of a parallel plate capacitor is:
As can be seen in the formula, capacitance C increases linearly with the area A (i.e. directly proportional to area A) and decreases with the distance D between the plates (i.e. inversely proportional to distance D).
Electronic symbol of a capacitor
You will observe that the electronic symbol of a capacitor is very appropriately drawn as two lines with a gap between the two lines. From the information presented so far, you can make the observation that a capacitor is an open circuit. No direct current can flow between the plates of the capacitor. A resistance measurement with an ohmmeter will give a reading of infinite ohms.
Properties of Capacitors
One of the early experiments with capacitors is with one known as the Leyden Jar. This consisted of a glass jar lined with lead foil on the inside and outside to form the plates of the capacitor. Early experimenters would charge the capacitor using static electricity by rubbing an ebony rod with wool or a glass rod with a silk cloth. As the story is told, in Paris in 1746, Abbé Nolle charged a Leyden and discharged it on a line of monks holding hands. The monks all jumped simultaneously as the electric charge traveled through their bodies.
Capacitors store charge
From this we observe that capacitors store electric charge.
Can capacitors serve as batteries? Yes, they can. Physical capacitance values range from 1pF to 1F which is a range of 12 orders of magnitude, 10 raised to the power 12. Capacitors with very high capacitances are not easy to make. A parallel plate air-gapped capacitor of 1F would be astronomically large and next to impossible to make. However, with advanced materials in dielectric materials, 1000F capacitors and even higher are now readily manufactured (albeit at low voltages, 2.7V). For obvious reasons, these are called super capacitors.
Here is a bank of 3000F 2.7V individual capacitors.
An electronic photo flash requires a burst of energy at 300V in a short duration to excite the xenon flash lamp. One 1.5V AA battery cannot supply that energy continuously. However, since the photo flash is only needed once with a long resting period, a 160μF capacitor is charged to the required 300V from a single 1.5V battery.
Capacitors take time to charge and discharge
If you charge a capacitor with a constant current I, the voltage on the capacitor rises linearly with time.
Let us look at the math.
The amount of charge (Q coulombs) placed on the capacitor is current (I amps) multiplied by time (t seconds).
Q = I x t
The attained voltage V (volts) on the capacitor is a function of the capacitance C (farads) and the charge Q.
Q = C x V
Putting the two equations together, we get
Q = I x t = C x V
or
V = I x t / C
A large capacitor takes longer to charge than a smaller capacitor.
If we were to charge the capacitor from a constant voltage, the charging current decreases (as an inverse exponential) as the difference in voltage between the source voltage Vs and the capacitor voltage Vc gets smaller. The charging current gets smaller and smaller. In theory, the voltage Vc on the capacitor never fully reaches the charging voltage Vs.
The take away here is that we can apply this behaviour of a capacitor in applications that involve time, for example, time delays, pulse widths, frequency, duration, etc.
To be continued in Part 2.
