Sources of electric energy in each area differ in the way it is received. So, in the steppes it is more expedient to use wind power or convert heat after burning fuel, gas. In the mountains, where there are rivers, dams are built and water drives giant turbines. Electromotive force is received almost everywhere due to other natural energies.
Where does consumer nutrition come from?
Sources of electrical energy receive voltage after the conversion of wind power, kinetic motion, water flow, the result of a nuclear reaction, the heat from the combustion of gas, fuel or coal. Widespread thermal power plants, hydroelectric power plants. The number of nuclear power plants as being not entirely safe for people living nearby is gradually decreasing.
A chemical reaction can be used, we observe these phenomena in the batteries of automobiles and household appliances. Batteries for phones work on the same principle. Vetroviki used in places with constant wind, where sources of electrical energy contain in the design of a conventional high-power generator.
To power an entire city, sometimes one station is not enough, and sources of electrical energy are combined. So, on the roofs of houses in warm countries, solar panels are installed that feed individual rooms. Gradually, environmentally friendly sources will replace stations that pollute the atmosphere.
In cars
The battery in vehicles is not the only source of electrical energy. Vehicle circuits are designed so that when moving, the process of converting kinetic energy into electrical energy begins. This is due to the generator, in which the rotation of the coils inside the magnetic field gives rise to the appearance of an electromotive force (EMF).
A current begins to flow in the network, charging the battery, the duration of which depends on its capacity. Charging starts immediately after the engine starts. That is, energy is generated by burning fuel. Recent developments in the automotive industry have made it possible to use the EMF of an electric energy source for traffic.
In electric vehicles, powerful chemical batteries generate current in a closed circuit and serve as a power source. Here the reverse process is observed: EMF is generated in the coils of the drive system, which makes the wheels spin. The currents in the secondary circuit are huge, proportional to the acceleration speed and the weight of the car.
The principle of operation of the coil with a magnet
The current flowing through the coil causes an alternating magnetic flux. He, in turn, exerts a buoyant force on the magnets, which makes the frame with two bipolar magnets spin. Thus, sources of electrical energy serve as a node for the movement of cars.
The reverse process, when the frame with the magnet rotates inside the windings, due to the kinetic energy allows you to convert the alternating magnetic flux into EMF coils. Further, voltage stabilizers are installed in the circuit, providing the required indicators of the supply network. According to this principle, electricity is generated in hydroelectric power plants, thermal power plants.
EMF in a circuit also appears in an ordinary closed circuit. It exists as long as a potential difference is applied to the conductor. An electromotive force is needed to describe the characteristics of an energy source. The physical definition of the term is as follows: the EMF in a closed circuit is proportional to the work of external forces that move a single positive charge through the entire body of the conductor.
Formula E = I * R - the resistance is taken into account the total sum of the internal resistance of the power source and the results of adding the resistance of the fed section of the circuit.
Substation Installation Limitations
Any conductor through which current flows produces an electric field. The energy source is an emitter of electromagnetic waves. Around powerful installations, at substations or near generating devices, human health is affected. Therefore, measures were taken to limit facilities under construction near residential buildings.
At the legislative level, fixed distances to electrical objects are established, beyond which a living organism is safe. It is forbidden to build powerful substations near houses and on the route of people. Powerful installations should have fences and closed entrances.
High-voltage lines are mounted high above buildings and carried out of settlements. To exclude the influence of electromagnetic waves in the residential area, energy sources are closed by grounded metal screens. In the simplest case, a wire mesh is used.
Units
Each value of the energy source and circuit is described by quantitative values. This facilitates the task of designing and calculating the load for a specific power supply. Units of measurement are interconnected by physical laws.
The following units are installed for the values of power supplies:
- Resistance: R - Ohm.
- EMF: E - volt.
- Reactive and impedance: X and Z - Ohm.
- Current: I - ampere.
- Voltage: U - volt.
- Power: P - Watt.
Construction of serial and parallel power circuits
The calculation of the circuit is complicated if a combination of several types of electrical energy sources is used. The internal resistance of each branch and the direction of the current through the conductors are taken into account. To measure the emf of each source individually, you will need to open the circuit and directly measure the potential at the terminals of the supply battery with a device - a voltmeter.
With a closed circuit, the device will show a voltage drop, which has a smaller value. Getting the right food often requires multiple sources. Depending on the task, several types of connections can be used:
- Sequential. EMF circuit of each source is added. So, when using two batteries with a nominal value of 2 volts, they get as a result of connecting 4 V.
- Parallel. This type is used to increase the capacity of the source, respectively, there is a longer battery life. EMF circuit with this connection does not change with equal battery ratings. It is important to observe the polarity of the compound.
- Combined connections are rarely used, but are found in practice. The calculation of the resulting EMF is performed for each individual closed area. The polarity and direction of branch current are taken into account.
Ohm mains
The internal resistance of the electric energy source is taken into account to determine the resulting EMF. In general, the electromotive force is calculated by the formula E = I * R + I * r. Here R is the resistance of consumers, and r is the internal resistance. The voltage drop is calculated according to the following relationship: U = E - Ir.
The current flowing in the circuit is calculated according to Ohm's law of the complete circuit: I = E / (R + r). Internal resistance can affect current strength. To prevent this from happening, the source is selected under load according to the following rule: the internal resistance of the source should be much less than the total total resistance of consumers. Then it is not necessary to take into account its value because of a small error.
How to measure ohms mains supply?
Since the sources and receivers of electrical energy must be coordinated, the question immediately arises: how to measure the internal resistance of a source? After all, an ohmmeter will not connect to contacts with the potentials available on them. To solve the problem, an indirect method of taking indicators is used - the values of additional quantities will be required: current and voltage. The calculation is performed according to the formula r = U / I, where U is the voltage drop at the internal resistance, and I is the current in the circuit under load.
The voltage drop is measured directly at the terminals of the power source. A resistor of known nominal R is connected to the circuit. Prior to measurements, the EMF voltage of the source should be fixed with an open circuit - E. Next, connect the load and record the readings - U load. and current I.
The desired voltage drop at the internal resistance U = E - U load. As a result, we calculate the desired value r = (E - U heat.) / I.