What is the difference between amperage current. What is the difference between current and voltage?

Voltage and current are quantitative concepts that should always be kept in mind when it comes to an electronic circuit. They usually change over time, otherwise the operation of the circuit is not of interest.

Voltage ( symbol U, sometimes E). Voltage between two points is the energy (or work) expended in moving a unit positive charge from a point of low potential to a point of high potential (i.e., the first point has a more negative potential compared to the second). In other words, it is the energy that is released when a unit charge “slides” from high potential to low. Voltage is also called potential difference or electromotive force. The unit of measurement for voltage is the volt. Typically, voltage is measured in volts (V), kilovolts, millivolts or microvolts (see section “Prefixes for forming multiples and submultiple units measurements", printed small print). In order to move a charge of 1 coulomb between points having a potential difference of 1 volt, it is necessary to do 1 joule of work. (The pendant serves as a unit of measurement electric charge And equal to charge approximately electrons.) Voltages measured in nanovolts or megavolts are rare; you will see this after reading the entire book.

We give names to generator voltage triggers such as battery and batteries. Other appliances, such as a refrigerator, washing machine, iron, blender, do not have such a button that allows you to adjust the voltage. If one of these devices is turned on at a voltage higher than the voltage specified by the manufacturer, it will burn almost immediately.

If it is connected to a voltage lower than specified, or the device does not work or performs poorly. Power is electrical quantity, which indicates the electrical energy consumption of the device at each moment of its operation. For example, if a lamp is rated at 100 watts, that means it consumes 100 joules of electricity every second. Most electrical appliances only have a wattage value, but there are some that provide more than one value, such as an electric shower.

Current (symbol). Current is the speed of movement of an electric charge at a point. The unit of measurement for current is ampere. Current is usually measured in amperes (A), milliamps, microamps

Nanoamps and sometimes picoamps. A current of 1 ampere is created by moving a charge of 1 coulomb in a time of 1 s. It is agreed that current in a circuit flows from a point with a more positive potential to a point with a more negative potential, although the electron moves in the opposite direction.

In this case, it usually has a value for the summer position and another for the winter position. In summer, when the water heats up less, the value is lower. In winter, when the water is hotter, the power value is greater, and therefore consumption electrical energy also more.

It is measured in kWh, which means kilogram watt-hour. This kilogram equal to a kilogram, kilometer and means 000 times. A watt-hour is already a measure of electrical energy. Although this may seem strange to you. This watt-hour is a unit of energy. Remember that a watt is a unit of force and an hour is a unit of time. Thus, a watt-hour is the product of power over time and 1 kWh is 000 watt-hour. At this stage we can take some beads of light which will be discussed with the students.

Remember: voltage is always measured between two points in a circuit, current always flows through a point in a circuit or through some circuit element.

You can’t say “voltage in a resistor” - it’s ignorant. However, we often talk about voltage at some point in the circuit. In this case, they always mean the voltage between this point and the “ground,” i.e., a point in the circuit whose potential is known to everyone. You will soon get used to this method of measuring voltage.

Electric current is a quantity whose value depends on the power of the device, as well as on the voltage at which it operates. For example, a 100-watt lamp rated at 110 volts requires more electrical current when connected than one rated at 60 watts at the same voltage. This is why a 100W bulb is brighter than a 60W bulb.

There are two types of electrical current: direct current, which is supplied from batteries, and alternating current, which is supplied from power plants to homes, industries, etc. Alternating current has a value that varies within a range during operation of the same electrical device.

Voltage is created by acting on electrical charges in devices such as batteries (electrochemical reactions), generators (interaction of magnetic forces), solar cells (photovoltaic effect of photon energy), etc. We obtain current by applying voltage between the points of the circuit.

Here, perhaps, the question may arise, what exactly are voltage and current, what do they look like? In order to answer this question, it is best to use an electronic device such as an oscilloscope. It can be used to observe voltage (and sometimes current) as a function that changes over time. We will resort to readings from oscilloscopes as well as voltmeters to characterize the signals. To begin with, we advise you to look at Appendix A, in which we're talking about about the oscilloscope, and Sect. "Universal measuring instruments", printed in small print.

In this case, it refers to the characteristic of alternating electric current obtained from electricity generating installations. In Brazil the frequency alternating current is 60 hertz, that is, 60 cycles per second. There are countries such as Portugal and Paraguay where the frequency is 50 hertz.

Understanding a little about souls

And for the summer. In which position is the current greater?

What energy transformation does a shower perform?
Where is he located?
When does the water get hot?
The resistor is divided into two sections.
What is the position and for the winter position?

In the summer position, the water heating is lower and corresponds to a lower shower power. In the winter position, the heating is higher and corresponds to higher power.

In real circuits, we connect elements to each other using wires, metal conductors, each of which at each point has the same voltage (relative to, say, ground). In the region of high frequencies or low impedances this statement is not entirely true, and we will discuss this issue in due course. Now let’s take this assumption on faith. We mention this to make you understand that the actual circuit does not have to look like the schematic diagram because the wires can be connected in different ways.

Connections in winter and summer correspond to the same voltage, to different powers. The thickness of the wound wire - resistor - commonly called "resistance" - is the same thing. Connections in winter and summer are obtained using different lengths resistors. IN summer time used for connection most of the same wire, and the winter connection is made using a small part of the wire, in the summer position a larger section is used.

In the winter connection, the current in the resistor must be higher than in the summer position, which allows for increased power and therefore heating. When the stress, material and thickness are kept constant, we can make the following relationship according to the following table.

Remember a few things simple rules concerning current and voltage.

1. The sum of currents flowing into a point is equal to the sum of currents flowing out of it (conservation of charge). This rule is sometimes called Kirchhoff's law for currents. Engineers like to call this point in the circuit a node. A corollary follows from this rule: in a series circuit (which is a group of elements that have two ends and are connected by these ends to one another), the current at all points is the same.

If we have a lamp with a power of 100 W with a voltage of 110 V, we have power P and the same lamp with a voltage of 220 V, what is the power in this case? Below are examples of activities with students in the classroom. In these activities, students will learn how to operate a multimeter, measure voltages, currents, etc.

Materials needed: multimeter, batteries and wires. If the teacher has resistors available for use, small circuits can be set up and more content covered. Figure 2 - Insert the batteries as shown in the figure below. In this assembly we were able to measure the potential difference between two lamps.

2. When connecting elements in parallel (Fig. 1.1), the voltage on each element is the same. In other words, the sum of the voltage drops between points A and B, measured along any branch of the circuit connecting these points, is the same and equal to the voltage between points A and B. Sometimes this rule is formulated as follows: the sum of the voltage drops in any closed loop of the circuit is zero. This is Kirchhoff's law for stress.

Figure 3 - Here we will measure the potential difference of the socket. Figure 4 - Value obtained with reference to Figure 3. From the experiments, students were able to plot a graph of voltage versus current, three measurements are enough to see the behavior of the graph.

The teacher can discuss slope lines and power. Voltage, current, ohms and power. Voltage can be compared to a building, the higher the voltage in the building, the lower the latter will be, the lower the voltage. In electronics, similarity is often used in a similar way to this, simply explaining a topic that would be difficult to understand on the fly without these tricks. As you can see in the picture, each floor costs 10 volts. The first building consists of a plane, so it costs 10 V, the second consists of 4 and the third costs 3.

3. Power (work done per unit time) consumed by the circuit is determined as follows:

Let's remember how we defined voltage and current, and we find that power is equal to: (work/charge) (charge/time). If the voltage U is measured in volts and the current I is measured in amperes, then the power P will be expressed in watts. Power of 1 watt is 1 joule of work done in 1 s.

The voltages in question are for the first floor, but if other references are made, everything changes. If everything is considered by the 2nd building, the first is -30V, the second is 0 and the third is -10V. To better understand the concept, just think about how you look at the buildings in question.

If you look at building 3, you'll see the first building with 20 floors running down to -20 volts, the second building with a floor over 10 volts, and the third where you're looking at 0 volts. The more electrons pass through in a second, the greater the current flowing through the conductor. The nature of current arises from the characteristic that two bodies have in contact in which they try to take on equal electrical charge in order to eliminate the energy level, this shift of the electron is called "current". Current is expressed in Ampere, a name derived from its discoverer, the French physicist André-Marie Ampere.

Power is dissipated as heat (usually) or sometimes expended in mechanical work (motors), converted into radiant energy (lamps, transmitters) or stored (batteries, capacitors). During development complex system one of the main ones is the question of determining its thermal load (take, for example, computer, in which the by-product of several pages of results from solving a problem is many kilowatts of electrical energy dissipated into space in the form of heat).

This law relates voltage and current to another parameter called "resistance". This can desired to say that current is directly proportional to voltage and inversely proportional to resistance. The formula of the law and its conclusions are as follows. With these formulas derived from the ohm law, various types of problems can be solved. In the first figure, you can calculate the current circulating in a simple circuit formed by a bulb, a battery and a conductor.

The light bulb has a filament that has some resistance. This other figure shows how to obtain voltage by knowing the current and resistance of an incandescent lamp. The other still depicts how to calculate the filament resistance by knowing the battery voltage and the current circulating in the circuit.

In the future, when studying periodically changing currents and voltages, we will have to generalize a simple expression in order to determine the average value of power. In this form it is valid for determining instantaneous value power.

By the way, remember that you don’t need to call current current intensity - it’s illiterate. You also cannot call a resistor a resistance. About resistors we'll talk in the next section.

In electronics, there are components called "resistors" that have a certain amount of resistance. These can be found at electronics stores or TV recyclers, but online they can buy them anywhere or salvage them from outdated or obsolete appliances. The side figure demonstrates resistance to metals.

Siemens is named after the physicist Werner von Siemens. When using hot water from an electric water heater or cooking or heating food on an electric stove, it unknowingly uses the Joule effect, in which resistance is part of these types of appliances or users.

Stupid question, you say? Not at all. Experience has shown that not many people can answer it correctly. Language also introduces a certain amount of confusion: in the expression “a source is commercially available” direct current 12 V" meaning is distorted. Actually in in this case This means, of course, a voltage source, not a current source, since current is not measured in volts, but it is not customary to say so. The most correct thing to say would be “DC power supply 12 volts”, but you can also write “power supply = 12V” where the “=” symbol means what it is constant pressure, not a variable. However, in this book we will also sometimes “make mistakes” - language is language.

To understand all this, let’s first recall the strict definitions from the textbook (memorizing them is very useful activity!). So, the current, or more precisely, its magnitude, is the amount of electric charge flowing through the cross-section of the conductor per unit time: / = Qlt. The unit of current is called “ampere”, and its dimension in the SI system is coulombs per second, knowledge of this fact will be useful to us later.

The definition looks much more confusing voltage - magnitude voltage is the difference electrical potentials between two points in space. It is measured in volts, and the dimension of this unit of measurement is joule per coulomb, that is, U – EIQ. Why this is so is easy to understand by delving into the meaning of the strict definition of voltage: 1 volt is such a potential difference at which moving a charge of 1 coulomb requires an expenditure of energy equal to 1 joule.

All this can be visualized by comparing a conductor with a pipe through which water flows. With this comparison, the magnitude of the current can be imagined as the amount (flow rate) of water flowing per second (this is a fairly accurate analogy), and the voltage as the pressure difference at the inlet and outlet of the pipe. Most often, the pipe ends with an open tap, so that the outlet pressure is equal to atmospheric pressure, and it can be taken as the zero level. Exactly the same in electrical diagrams there is a common wire (or “common bus” - in common parlance it is often called “ground” for brevity, although this is not exact - we will return to this issue later), the potential of which is taken to be zero and against which all voltages in scheme. Usually (but not always!) the negative terminal of the main power supply of the circuit is taken as the common wire.

So, back to the question posed in the title: what is the difference between current and voltage? The correct answer will be: current is the amount of electricity, and voltage is a measure of it potential energy. An interlocutor who is inexperienced in physics, of course, will begin to shake his head, trying to understand, and then such an explanation can be given. Imagine a falling stone. If it is small (the amount of electricity is small), but falls from high altitude(high voltage), then it can cause as many misfortunes as a large stone (lot of electricity), but falling from a low height (low voltage).

As soon as we start studying school curriculum physics, almost immediately our teachers begin to tell us that between current and voltage there is a very a big difference, and we will desperately need its knowledge in later life. And yet, now even an adult cannot tell about the differences between the two concepts. But everyone needs to know this difference, because we deal with current and voltage Everyday life, for example, by plugging in a TV or phone charger.

Definition

Electric shock called the process when under the influence electric field the ordered movement of charged particles begins. Particles can be the most different elements, it all depends on specific case. If we are talking about conductors, then the particles in this situation are electrons. Studying electricity, people began to understand that the capabilities of current allow it to be used in the most different areas, including medicine. After all, electrical charges help to resuscitate patients and restore heart function. In addition, current is used in the treatment of complex diseases such as epilepsy or Parkinson's disease. In everyday life, it is simply irreplaceable, because with its help the lights are on in our apartments and houses and electrical appliances work.

Voltage- a concept much more complex than current. Single positive charges are moving from different points: from low to high potential. And voltage is the energy spent on this movement. For ease of understanding, an example is often given with the flow of water between two banks: the current is the flow of water itself, and the voltage shows the difference in levels in the two banks. Accordingly, the flow will continue until the levels are equal.

Difference

Probably, the main difference between current and voltage could be noticed already from the definition. But for convenience, we will present two main differences between the concepts under consideration with a more detailed description:

Current is an amount of electricity, while voltage is a measure of potential energy. In other words, both of these concepts are highly dependent on each other, but at the same time they are very different. I (current) = U (voltage) / R (resistance). This is the main formula by which you can calculate the dependence of current on voltage. Resistance is affected whole line factors, including the material from which the conductor is made, temperature, external conditions.
The difference is in the receipt. Exposure to electrical charges in various devices (such as batteries or generators) creates voltage. And the current is obtained by applying voltage between the points of the circuit.

The inability to see electric current and charge flow in person has always been a problem for those trying to comprehend basic electrical concepts. The two main components of research, current and voltage, are typically misinterpreted by those trying to understand the topic. This article will help you understand the difference between them.

The basic concepts of electricity revolve around one atomic component: the electron. Unstable atoms have either a deficiency or additional electrons in their valence band. Excess electrons from one unstable atom tend to the valence band of an atom that has an electron deficiency.

Using an external electrochemical source, electron movement can be created. Any two terminals can be used to connect this charge source and create two contacts, one with positive potential and the other with negative potential.

The potential difference between two such points, one of which acts as a source and the other as a receiver of electrons, is called voltage. The unit of measurement for voltage is the volt, and its symbol is " V".

The flow of electrons in a conductor causes a current. The direction of the current goes from the positive pole to the negative pole. But electrical charges, i.e. electrons, actually travel from the negative to the positive potential of the source. The amount of electrical charge flowing through a unit cross-sectional area of a conductor is called current. Current strength is measured in amperes, and has the symbol “ I".

Circuit breakers

A fuse is used in an electrical circuit and electrical work to interrupt the flow of excessive current through its components. Manufacturers of electrical fuses indicate characteristics using two parameters - voltage and current. The criteria for selecting a fuse depend on the rated voltage of the circuit in which it will operate.

The current characteristics of the fuse do not depend on the type of current flowing through it - alternating or direct. This depends only on the magnitude of the current at the moment the fusible wire melts. Although the thickness of the wire and the type of metal wire used is a factor directly related to the current performance of the equipment. This is because the heat generated by the fuse wire is a function of the square of the current flowing through the conductor multiplied by the resistance and the time the current flows.

Effect of batteries on current and voltage

Rechargeable batteries are typically rated by the current (amps) they can supply continuously for one hour. Therefore, battery characteristics are indicated in ampere hours. The battery life depends on the load connected through it. Heavy loads tend to shorten battery life, while light loads increase battery life.

If the batteries are connected in series in an electrical circuit, the power supply network, the voltage in the circuit will increase, but the current in the circuit will remain at the same level.

Parallel connection of voltage sources is used to increase the current without increasing the voltage.

Water flow analogy

Consider two reservoirs connected by a transparent tube; the water in them is kept at the same height from the ground. There is no water flow in the tube.

Now if we change the position of one of the tanks to create a potential difference, we will notice that water flows through the tube from the container with great potential into a container with a lower potential. Instead of changing the level of water bodies, we can also use water pumps for the same purpose. Valves can be used to regulate the amount of water flowing in a pipe from one reservoir to another.

An analogy can be drawn between this situation and a simple electrical circuit. A water pump is used to create water pressure in a stream, let's call it "tension". Water behaves like charged electrons. The flow of water is similar to the movement of electrons, and the amount of water flowing through a unit area cross section pipes is similar to “current strength”. The higher potential reservoir is the "power source" and the amount of water it contains is the "battery capacity". Any valve installed along a pipe can be considered a “load”. electric installation work

Stupid question, you say? Not at all. Experience has shown that not many people can answer it correctly. The language also introduces some confusion: in the expression “a 12 V source is available for sale” the meaning is distorted. In fact, in this case we mean, of course, a voltage source, not a current source, since current is not measured in volts, but it is not customary to say so. The most correct thing to say would be “DC power supply 12 volts”, but you can also write “power supply = 12V” where the “=” symbol means that this is direct voltage and not alternating. However, in this book we will also sometimes “make mistakes” - language is language.

To understand all this, first let’s recall the strict definitions from the textbook (memorizing them is a very useful activity!). So, the current, or more precisely, its magnitude, is the amount of electric charge flowing through the cross-section of the conductor per unit time: / = Qlt. The unit of current is called “ampere”, and its dimension in the SI system is coulombs per second, knowledge of this fact will be useful to us later.

The definition of voltage is much more confusing - the magnitude of voltage is the difference in electrical potential between two points in space. It is measured in volts, and the dimension of this unit of measurement is joule per coulomb, that is, U – EIQ. Why this is so is easy to understand by delving into the meaning of the strict definition of voltage: 1 volt is such a potential difference at which moving a charge of 1 coulomb requires an expenditure of energy equal to 1 joule.

All this can be visualized by comparing a conductor with a pipe through which water flows. With this comparison, the magnitude of the current can be imagined as the amount (flow rate) of water flowing per second (this is a fairly accurate analogy), and the voltage as the pressure difference at the inlet and outlet of the pipe. Most often, the pipe ends with an open tap, so that the outlet pressure is equal to atmospheric pressure, and can be taken as zero. Similarly, in electrical circuits there is a common wire (or "common bus" - colloquially for brevity it is often called "ground", although this is not exact - we will return to this issue later), the potential of which is taken to be zero and relative to which All voltages in the circuit are read from. Usually (but not always!) the negative terminal of the main power supply of the circuit is taken as the common wire.

So, back to the question posed in the title: what is the difference between current and voltage? The correct answer would be: current is the amount of electricity, and voltage is a measure of its potential energy. An interlocutor who is inexperienced in physics, of course, will begin to shake his head, trying to understand, and then such an explanation can be given. Imagine a falling stone. If it is small (little amount of electricity) but falls from a great height (high voltage), then it can cause as much misfortune as a large stone (lot of electricity) but falling from a low height (low voltage).

What is the difference between current and voltage?

Therefore, it will be easier for me, facilius natans, to take a topic of my choice, which for these difficult questions theology would be what morality is to metaphysics and philosophy.

A. Dumas. Three Musketeers

Stupid question, you say? Not at all. Experience has shown that not many people can answer it correctly. The language also introduces some confusion: in the expression “a 12 V DC source is commercially available” the meaning is distorted. In fact, in this case we mean, of course, a voltage source, not a current source, since current is not measured in volts, but it is not customary to say so. The most correct thing to say would be “DC power supply 12 volts”, but you can also write “power supply = 12V”, where the “=” symbol means that this is direct voltage and not alternating voltage. However, in this book we will also sometimes “make mistakes” - language is language.

To understand all this, let’s first recall the strict definitions from the textbook (memorizing them is a very useful activity!). So, current, more precisely, its value is the amount of electric charge flowing through a cross-section of a conductor per unit time : I = Q /t. The unit of current is called the ampere, and its SI unit is coulombs per second. Knowing this fact will be useful to us later.

The definition of voltage looks much more confusing - the magnitude of the voltage is the difference in electrical potential between two points in space. It is measured in volts, and the dimension of this unit of measurement is joule per coulomb, i.e. U = E /Q. Why this is so is easy to understand by understanding the meaning of the strict definition of voltage: 1 volt is the potential difference at which moving a charge of 1 coulomb requires energy equal to 1 joule .

All this can be visualized by comparing a conductor with a pipe through which water flows (and this will be a fairly accurate analogy). With this comparison, the current value can be imagined as the amount (flow rate) of water flowing per second, and the voltage as the pressure difference at the inlet and outlet of the pipe. Most often, the pipe ends with an open tap, so that the outlet pressure is equal to atmospheric pressure, and can be taken as zero. In the same way, in electrical circuits there is a common wire (or “common bus” - in common parlance it is often called “ground” for brevity, although this is not exact - we will return to this issue later), the potential of which is taken to be zero and relatively which all voltages in the circuit are measured. Usually (but not always!) the negative terminal of the main power supply of the circuit is taken as the common wire.

Circuit breakers

Effect of batteries on current and voltage

If the batteries are connected in series in an electrical circuit, the power supply network, the voltage in the circuit will increase, but the current in the circuit will remain at the same level.

Parallel connection of voltage sources is used to increase the current without increasing the voltage.

Water flow analogy

Consider two reservoirs connected by a transparent tube; the water in them is kept at the same height from the ground. There is no water flow in the tube.

Now, if we change the position of one of the reservoirs to create a potential difference, we will notice that water flows through the tube from the container with a higher potential to the container with a lower potential. Instead of changing the level of water bodies, we can also use water pumps for the same purpose. Valves can be used to regulate the amount of water flowing in a pipe from one reservoir to another.

An analogy can be drawn between this situation and a simple electrical circuit. A water pump is used to create water pressure in a stream, let's call it "tension". Water behaves like charged electrons. The flow of water is analogous to the movement of electrons, and the amount of water flowing through a unit cross-sectional area of a pipe is analogous to the "current strength". The higher potential reservoir is the "power source" and the amount of water it contains is the "battery capacity". Any valve installed along a pipe can be considered a “load”. electric installation work