For a person who is familiar with electrical equipment on the level of a simple user (knows where and how to turn on / off), many of the terms used by electricians seem to be some kind of nonsense.For example, which is only "voltage drop" or "circuit assembly".Where and what falls?Who made out on the details of the scheme?In fact, the physical meaning of the processes, lurking behind most of these words, it is easy to understand, even with school knowledge of physics.
to explain what the voltage drop, it is necessary to remember what all the voltage in an electrical circuit are (referring to the global classification).There are only two types.The first - is the supply voltage, which is connected to the circuit under consideration.It may also be referred to throughout the attached chain.And the second type - this is the voltage drop.It can be considered both in terms of the entire circuit, and any other single element.
In practice it looks as follows.For example, if you take an ordinary bulb, screw it into the socket, and connect the wires from it into a home wall outlet, then applied to the circuit (power supply - Guides - load), the voltage will be 220 volts.But if we use a voltmeter to measure the value of the lamp, as will become evident that it is a little less than 220. This happened because there was a voltage drop in the electrical resistance, which has a lamp.
Perhaps there is no person who has not heard about Ohm's law.In general, the wording of his looks:
I = U / R,
where R - resistance of the circuit or component, measured in ohms;U - voltage, in volts;and finally, I - current in amperes.As you can see, all three values are directly linked.Therefore, knowing any two can be quite simple to calculate the third.Of course, each case would have to take into account the type of current (AC or DC) and some other qualifying characteristics, but the basis - the above formula.
electrical energy - is, in fact, the movement of the conductor of negatively charged particles (electrons).In our example, the spiral lamp has a high resistance, that is, slow moving electrons.This results in a visible glow, but the total energy of the particle flux is reduced.As seen from the formula, it decreases with decreasing current and the voltage.That is why the results of measurements at the outlet and the lamp is different.This difference is the voltage drop.This value is always taken into account to prevent too great a reduction of cells in the end of the circuit.
voltage drop across the resistor depends upon its internal resistance and the strength of the current flowing through it.Also indirectly influenced by the temperature and current characteristics.If in the chain include an ammeter, the drop can be determined by multiplying the current value on the resistance of the lamp.
But not always possible just like that with a simple formula, and the measuring device to perform the calculation of the voltage drop.In the case of parallel connected resistors finding magnitude more complicated.On the AC has to take into account an additional reactive component.
Consider the example of two parallel-connected resistors R1 and R2.Known wire resistance R3 and the power supply R0.Also, given the importance of the EMF - E.
Here is a parallel branch to a single number.For this situation, use the formula:
R = (R1 * R2) / (R1 + R2)
determines the resistance of the whole chain of the sum of R4 = R + R3.
expect current:
I = E / (R4 + r)
remains to learn the value of the voltage drop at the chosen element:
U = I * R5
Here the factor "R5" can be any R - 1 to 4, depending on which circuit element is to be calculated.
