What is the essence of electric current?

What is the essence of electric current? The textbook says that it is the directional movement of electrons. Does this movement circle around the circuit or oscillate nearby? Are electrons an entity, so why does AC power pass through a capacitor, and if it’s not an entity, what is emitted by the TV picture tube? Thanks for the advice. And why can the earth be used as a wire?

What is the essence of electric current?
What is the essence of electric current?

We need more than just a continuous path (i.e., a circuit) before constant charge flow can occur: we also need some way to push these charge carriers around the course, like marbles in a tube or water in a box. It takes some force to turn on the flow. For electrons, this force is the same force that works in static electricity: the force created by the charge imbalance. If we take the example of rubbing between wax and wool cloth, we will see that the excess of electrons in the wax (negative charge) and the lack of electrons in the wool cloth (positive control) create a charge imbalance between them. This imbalance manifests as an attractive force between two objects:

Wax, attraction, and wool cloth

If you put a wire between the charged wax and the wool cloth, electrons will flow through it because some of the excess electrons in the resin will rush through the wire back to the wool cloth, filling the electron deficit there:

Electron Flow
Electron Flow

Electron Flow and Wire/conductor

The electron imbalance between the atoms is in the wax. And the particles in the wool cloth create a force between the two materials. Since there is no path for electrons to flow from the wax to the wool cloth, this force can attract the two objects together. However, now that the conductor spans the insulating gap, the pressure will cause the electrons to flow in a uniform direction through the wire, even if only temporarily. Until the charge in the area is neutralized and the force between the wax and the fleece is reduced. By rubbing the two materials together, the head formed between the two materials is used to store a certain amount of energy. This energy is not dissimilar to that stored in high reservoirs, which are drawn from lower-level ponds:

Energy Stored
Energy Stored

Energy Stored, Reservoir, Water Flow, Pump and Pond

The gravity on the water creates a force that tries to move the water down to a lower level. If suitable pipes flow from the reservoir back to the pond, water will flow from the reservoir through the pipes under the influence of gravity:

Energy Released
Energy Released

Energy Released

It takes energy to pump water from a low-level pond to a high-level reservoir. The water moves back through the pipe to its original water level, releasing the energy stored by the previous pumping. If the water is pumped to a higher level, more power will be required, will store so more energy, and will release more energy if the water is allowed to flow back through the pipe again: (Note: raising the water level absorbs energy, lowering the water level to release energy)

More Energy Stored
More Energy Stored

More Energy Stored and More Water Flow

Electrons are not very different from the water situation described above. If we rub the wax and wool cloth together, we “pump” the electrons away from their usual “level,” creating a force between the wax and the wool cloth as the electrons try to re-establish their previous positions (and Atoms within them are in equilibrium). The point that draws the electron back to its original position around the positive nucleus of the atom is similar to the force that gravity exerts on the water in a reservoir, trying to pull it back to its original level. Just as pumping water to a higher level causes energy to be stored, “pumping” electrons to create a charge imbalance causes a certain amount of energy to be held in that imbalance. And, just as providing a way for water to flow back down from the height of the reservoir results in the release of stored energy, providing a way for electrons to drift back to their original “level” results in the release of stored energy. When charge carriers are at rest (like water standing still, high up in a reservoir), the energy stored there is called potential energy.

Note: I can understand it in this way that the earth is an atom, the objects falling on the planet are electrons, and particles have a gravitational effect on electrons, just like the earth has a gravitational impact on other things.

1. Understand the concept of voltage.

When a charge carrier is at rest (like water standing still, high up in a reservoir), the energy stored there is called potential energy because it has the possibility of release that has not been fully realized ( potential energy). When you rub your rubber-soled shoes against a fabric rug on a dry day, you create a charge imbalance between yourself and the carpet. The act of wiping your feet stores energy in the form of unbalanced charges that are forcibly released from their original location. This charge (static) is static, and you don’t even realize that energy is being stored. But once you put your hand on the metal doorknob (which has a lot of electron mobility to neutralize your charge), it will release the stored energy in the form of a sudden flow of charge through your hand, and you will feel it as a kind of electric shock! This potential energy, stored in the form of a charge imbalance that can excite charge carriers to flow through the conductor, can be expressed in terms of voltage, which is technically a measure of the potential energy per unit charge or what physicists would call specific potential energy.

2. Definition of Voltage

Defined in the context of electrostatics, voltage measures the amount of work required to move a unit of charge from one location to another against the forces trying to keep the costs in balance. In the context of power supplies, voltage is the potential energy (work to be done) available per unit of account to move the head through a conductor. Because voltage is an expression of potential energy, representing the possibility or potential for energy release, it must have two reference points when a charge moves from one “level” to another. Consider the analogy of a reservoir:

Drop and Location 1
Drop and Location #1

Drop and Location #1

Due to the difference in drop height, more energy is released from the reservoir to location 2 than to location 1. This principle can intuitively understand as dropping a rock: does this result in more slamming, a stone falling from a height of afoot. Or the same stone falling from a height of a mile? Higher altitude descents result in more energy release (more violent impacts). We cannot estimate the amount of energy stored in a reservoir just by measuring the volume of water, just as we cannot predict the severity of the impact of a falling rock simply by knowing the weight of the stone. We must also consider How far these masses will drop from their initial heights in both cases. The energy released by a drop-in group is related to the distance between its starting and ending points. Likewise, the potential energy available to move charge carriers from one point to another is related to these two points. Therefore, voltage is always expressed as a quantity between two points. Interestingly, the analogy that mass may “drop” from one height to another is an apt model that the voltage between two points is sometimes called a voltage drop.

3. Generating Voltage

In addition to rubbing certain types of materials against each other, there are other ways to generate voltage. Chemical reactions, radiant energy, and the effect of magnetism on conductors are a few ways in which voltage is generated. Corresponding examples of these three voltage sources are batteries, solar cells, and generators (such as the “alternator” unit under the hood of a car). We won’t go into the details of how these voltage sources work – what’s more important is that we understand how to apply a voltage source to generate a flow of charge (current) in a circuit. Let’s build the circuit step by step in the notation of a chemical battery: (A voltage source is a device, source object, substance that produces a voltage)



4. How does the voltage source work?

Any voltage source, including batteries, has at least two electrical contacts. In this case, we have points 1 and point 2 in the image above. Horizontal lines of varying lengths indicate that this is a battery. They further indicate that the battery’s voltage will try to push the charge carriers through the circuit. The fact that the horizontal lines in the battery symbol appear to be separate (and therefore cannot be used as paths for the charging flow) is nothing to worry about. In real life, these horizontal lines represent metal plates immersed in a liquid or semi-solid material that not only conducts charge; They can also be propelled forward by generating a voltage through interaction with the plates. Note the small “+” and “-” symbols to the left of the battery symbol. The battery’s negative (-) end is always the end of the dashed line, and the positive (+) end of the battery is always the end of the long dashed line. The positive side of the battery is the end that tries to push the charge carrier out of the battery (remember, by convention, we think of the charge carrier as positively charged, even though the electron is negatively charged). Again, the opposing end is the end that is trying to attract charge carriers. Since nothing is connected to the “+” and “-” ends of the battery, there will be a voltage between these two points, but no charge will flow through the battery because there is no continuous path for the carriers to move.

Water Analog
Water Analog

Electric Battery, No Flow, Water Analog, and No Flow(once the reservoir has been filled)

The same principle applies to the pool and pumps analogy. If the reservoir has been filled, Without a return pipe back to the pond, it cannot release the energy stored in the pond in water flow. Once the reservoir is full, no flow will occur, no matter how much pressure the pump produces. There needs to be a complete path (loop) to flow from the pond to the reservoir and back to the pond for continuous flow. We can provide such a path for the battery by connecting a wire from one end to the other. Forming a circuit with a loop of wire, we will initiate a continuous flow of charge in a clockwise direction:

Electric Circuit Circuit Charge Flow! Charge Flow Energy Analog

5. Understand the concept of current

As long as the battery continues to produce voltage and the continuity of the circuit is not interrupted, the charge carriers continue to flow in the course. Following the analogy of water flowing through a pipe, this continuous, uniform flow of electric charge through a circuit is called current. As long as the voltage source remains “pushing” in the same direction, the charge carriers continue to move in the same order in the circuit. This unidirectional current is called direct current (DC). In the second volume of this book series, a course in which the current direction is switched back and forth is explored: Alternating Current (AC). But for now, let’s focus on the DC circuit. Because current is made up of individual charge carriers that flow in unison through conductors by moving and pushing the charge carriers forward, like a marble through a pipe or water through a line, the flow through a single circuit is the same. If we were to monitor the cross-section of a wire in a single course, counting the charge carriers flowing through, we would notice that the amount per unit time is the same as any other part of the circuit, regardless of conductor length or conductor diameter. If we break the continuity of the course at any time, the current will stop throughout the period, and the total voltage produced by the battery will manifest at the breakpoint:

Voltage drop/voltage difference (Note voltage difference at the point of disconnection = battery voltage)

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No Flow No current

break disconnection/interruption

6. What is the polarity of the voltage drop?

Note the “+” and “-” symbols are drawn at the open ends of the circuit. And how they correspond to the “+” and “-” signs next to the battery terminals. These markings indicate how the voltage is trying to push the current. The direction of the potential is commonly referred to as polarity. Remember that voltage is always relative between two points. The polarity of the voltage drop is also relative between two points: whether a point in the circuit is marked “+” or “-” depends on the other end it refers to. Take a look at the course below. Where each corner of the loop is marked with a number for reference:

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When the circuit is broken between points 2 and 3. the voltage’s polarity dropped between points 2 and 3 is “+” at point 2 and “-” at point 3. The polarity of the battery (1″+” and 4″-“) is trying to push the current clockwise, from 1 to 2 to 3 to 4 and back to 1 again. Now let’s see what happens if we reconnect points 2 and 3 together again (put a breakpoint in the circuit between points 3 and 4):

v2 01649fbedea00661aad2efdf2e09ac20 720w

When disconnected between 3 and 4, the voltage drop polarity between these two points is “-” for four and “+” for 3. Pay special attention to the fact that the “sign” of point 3 is the opposite of the first. For example, the breakpoint is between points 2 and 3 (where point 3 is marked with a “-“). We can’t say that point 3 in this circuit is always “+” or “-” because polarity, like voltage itself, is not specific to a single point, but between two points, always relative!

7. Summary

Charge carriers can be excited to flow through the conductor by the same force as static electricity.

Voltage measures potential energy (per unit charge) between two locations. In layman’s terms, it’s a measure that can be used to “push” an electric bill to move.

As an expression of potential energy, voltage is always relative between two locations or points. Sometimes it’s called voltage drop.

When a voltage source is connected to a circuit, the voltage[1] will cause charge carriers to flow uniformly through the course, known as current.

In a single (one loop, one loop, no branches) circuit, the amount of current at any point is the same as the amount of current at any other issue.

If a circuit containing a voltage source is disconnected, the total voltage of that source will appear at the disconnection point.

The +/- direction of the voltage drop is called polarity. It is also relative between two points.

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