What is an electric charge in what units is it measured
Discovery history
Even in antiquity it was noticed that if you rub amber on silk matter, then the stone will begin to attract light objects. William Hilbert studied these experiments until the end of the 16th century. In the progress report, objects that can attract other bodies are called electrified.
The following discoveries in 1729 were made by Charles Dufe, observing the behavior of bodies during their friction against different matters. Thus, he proved the existence of two types of charges: the first are formed by the friction of resin on wool, and the second by friction of glass on silk. Following the logic, he called them “tar” and “glass”. Benjamin Franklin also investigated this issue and introduced the concepts of positive and negative charge. In the illustration - B. Franklin catches lightning.
Charles Coulomb, whose portrait is depicted below, discovered the law, which was later named Pendant law. He described the interaction of two point charges. I was also able to measure the value and invented for this torsion balance, which we will discuss later.
And at the beginning of the last century, Robert Milliken, as a result of the experiments, proved their discreteness. This means that the charge of each body is equal to the whole multiple of the elementary electric charge, and the electron is elementary.
Theoretical information
An electric charge is the ability of bodies to create an electromagnetic field. In physics, the electrostatics section studies the interactions of motionless charges relative to the selected inertial system.
What is measured
The unit of measurement in the SI system is called "Coulomb" - this is an electric charge passing through the cross section of a conductor of 1 Ampere in 1 second.
The letter designation is Q or q. It can take both positive and negative values. The name is in honor of the physicist Charles Coulomb, he derived a formula for finding the forces of interaction between them, it is called the "Law of Coulomb":
In it, q1, q2 are the charge modules, r is the distance between them, k is the coefficient of proportionality.
The formula is similar to the law of attraction, in principle, it describes a similar interaction. It has the smallest mass. Its electric charge is negative and it is equal to:
-1.6 * 10 ^ (- 19) C
A positron is the opposite value to an electron; it also consists of one positive elementary charge.
Besides the fact that it is discrete, quantized or measured in portions, the Law of conservation of charges is also valid for it, which says that in a closed system charges of both signs can occur only simultaneously. In simple terms, the algebraic (taking into account the signs) sum of the charges of particles and bodies in a closed (isolated) system always remains unchanged. It does not change with time or with the movement of a particle; it is constant during its lifetime. The simplest charged particles are conventionally compared with electric charges.
The law of conservation of electric charges was first confirmed by Michael Faraday in 1843. This is one of the fundamental laws of physics.
Conductors, Semiconductors and Dielectrics
There are many free charges in conductors. They move freely throughout the body. There are almost no free carriers in semiconductors, but if a little energy is transferred to the body, they are formed, as a result of which the body begins to conduct an electric current, i.e. electric charges begin to move. Dielectrics are substances where the number of free carriers is minimal, so the current cannot flow through them or can, under certain conditions, for example, a very high voltage.
What is the interaction
Electric charges are attracted and repelled from each other. This is similar to the interaction of magnets. Everyone knows that if you rub a ruler or ballpoint pen on your hair, it will become electrified. If in this state you bring it to the paper, then it will stick to the electrified plastic. During electrification, redistribution of charges occurs, so that on one part of the body they become larger, and on the other less.
For the same reason, you are sometimes shocked by a wool sweater or other people when you touch them.
Conclusion: electric charges with one sign tend to each other, and with different signs they repel each other. They flow from one body to another when they touch each other.
Measurement methods
There are a number of ways to measure electric charge, let's look at some of them. The measuring device is called a torsion balance.
Pendant Scales are the torsion scales of his invention. The point is that a light rod with two balls at the ends and one stationary charged ball are suspended in a vessel on a quartz thread. The second end of the thread is fixed to the cap. The stationary ball is removed in order to tell it the charge, after that you need to install it back into the vessel. After that, the part suspended on the thread will begin to move. A graduated scale is marked on the vessel. The principle of its action is reflected in the video.
Another device for measuring electric charge is an electroscope. It, like the previous ones, is a glass vessel with an electrode on which two metal sheets of foil are fixed. The charged body is brought to the upper end of the electrode, along which the charge flows onto the foil, as a result, both leaves will be charged with the same name and begin to repel. The amount of charge is determined by how much they deviate.
An electrometer is another measuring device. Consists of a metal rod and a rotating arrow. When a charged body touches the electrometer, charges flow down the rod to the arrow, the arrow deviates and indicates a certain value on the scale.
In the end, we recommend watching another useful video on the topic:
We examined an important physical quantity. Teachings about it have significantly expanded knowledge of electricity in general. The contribution to science and technology is quite significant, and the field of application of this knowledge is also related to medicine. Air ionizers have a positive effect on the human body: they accelerate the process of oxygen delivery from air to cells. An example of such a device is the Chizhevsky chandelier.Now you know what an electric charge is and how it is measured.
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