What is direct current, what is direct current ?

It refers to a current whose direction does not change over time, but the magnitude of the current may not be fixed, resulting in a waveform. Also known as:

Constant current. The circuit that passes through is called.

DC circuits. It is a closed conductive circuit consisting of a DC power supply and a resistor. In this circuit, a constant electric field is formed, outside the power supply, the positive charge flows from the high potential to the low potential through resistance, and in the power supply, the electrostatic force is overcome by the action of the non-electrostatic force of the power supply, and then from the low potential to the high potential, and so on, forming a closed current line.

Therefore, in a DC circuit, the role of the power supply is to provide a constant electromotive force that does not change with time, supplementing the Joule heating consumed on the resistor.

The current whose magnitude and direction change periodically with time is alternating current, also known as alternating current, which usually refers to sinusoidal current, and the current whose magnitude and direction do not change with time is called direct current, also known as constant current.

The direction of the direct current is always the same, but the magnitude can be changed.

Our ordinary electricity consumption is alternating current, but the frequency of alternating current in foreign countries is larger.

At present, there are also a small number of advanced areas in the world where electricity is DC.

Current flows in only one direction, e.g. a battery is a direct current.

The charge flows in an unchanging direction, which is called "direct current".

A current whose direction does not change with time is a direct current.

The direction of the direct current does not change. The size can be varied. Alternating current is changed in size and direction. There are many, many waveforms.

The direction of the current does not change with time.

Direct current vs. alternating current.

General concept. Direct current: Refers to an electric current that does not change in magnitude and direction with time.

Many electrical appliances, such as radios, speakers, and many other appliances that do not contain inductive components, are driven by DC hidden electricity. It is divided into positive and negative poles, and the voltage cannot be changed by using a transformer, so it is used in low-voltage electrical appliances. Appliances with dry batteries fall into this category.

Alternating current: Alternating current refers to the current whose magnitude and direction change periodically with time, and the usual alternating current changes according to the law of sine or cosine, and the current first changes from zero to maximum, and then from maximum to zero. Then the reverse direction changes from zero to maximum, and then from maximum to zero, completing one cycle, and then the next cycle, and so on.

In addition to being used for some special electrical appliances, such as motors, it also has special significance for the transmission of power distribution, especially long-distance transmission.

When one pole of alternating current is positive, the other pole is negative, constantly changing (the household power supply changes 50 to 60 times per second plus or minus), alternating current can use a transformer to change the voltage, and it becomes a high-voltage transportation of hundreds of thousands of volts during long-distance transportation, which can reduce the loss due to resistance. Large household appliances, such as refrigerators, TVs, air conditioners, etc., all use alternating current.

Direct current: An electric current that is conducted in a circuit in a constant direction. This current is used in electrolysis, DC motors, and telecommunications. Direct current can be obtained by using a DC generator, a battery, or by passing alternating current through a rectifier.

Alternating current: An electric current that changes in direction and intensity periodically. The advantage of this current is that the voltage can be changed with a transformer. At present, the direction and intensity of alternating current used in industry and daily life generally change 50 times per second.

The DC voltage will not change its voltage amplitude and direction with the continuation of time, and the voltage amplitude and direction of the AC voltage will change periodically with the continuation of time.

Applications of DC in daily life:

All batteries or accumulators are DC motors, such as: toy motors, toy cars, toy airplanes, razors, rechargeable power tools, etc.

Application of alternating current in daily life:

The advantage that alternating current is easy to transmit. Easy to buck and down. The lighting electricity in daily life is alternating current, and most of the electricity in the industry is also AC type, even if you need to know how to use DC, it is also AC mode transmitted to the site in the conversion to DC.

A: No, it is not. Explanation:

AC power AC indicated. (The alternating current is codenamed AC, and the symbol is a sine wave.)

A single represents the current and the unit is amperes.

DC code DC, the symbol is a horizontal horizontal "one", if you want to mark the positive and negative polarity of a certain component, only use + - to indicate.

Introduction: Alternating current (abbreviated AC) refers to an electric current that changes periodically in both magnitude and direction, because the average operating value of periodic current in a cycle is zero, which is called alternating current or alternating current for short. The direction of direct current is the same.

Usually the waveform is sinusoidal. Alternating current can transmit electricity efficiently. But there are actually other waveforms that are used, such as triangular waves, square waves.

The mains power used in daily life is alternating current with a sinusoidal waveform.

Average: When the amount of AC picodifference through the conductor cross-section of the circuit is equal to the amount of electricity q that has been flowing through the conductor cross-section of the circuit in the same time in the same time, the value of the direct current is called the average value of the alternating current in the half cycle.

The (t+) in i=imsin( t+ ) in alternating current is called phase (phase angle). It characterizes the state that the function reaches at a certain point in the process of change. For example, in the phase, the phase where the zero value is reached when t+ = 0, and so on.

is the phase when t = 0, which is called the initial phase. In a practical problem, what is more important is the phase difference between two alternating currents.

Rectification: The process of converting alternating current into direct current is called "alternating current rectification". Rectification can be divided into several forms, such as half-wave rectification, full-wave rectification, and bridge rectification. Conventional rectifiers use the unidirectional conductivity of electron tubes and crystal diodes to rectify the current.

Half-wave rectification] During rectification, only one and a half cycles of alternating current pass through the rectifier. Half-wave rectification is the simplest rectifier, but it is very inefficient, and it is difficult to smooth the current waveform of the rectified current.

Full-wave rectification] A circuit that rectifies AC. In this type of rectifier circuit, current flows through one rectifier device (e.g., a crystal diode) for half a cycle, and over the other half a cycle, through a second rectifier device, and the connection of the two rectifier devices causes the current flowing through them to flow through the load in the same direction.

Bridge rectification】 Bridge rectification is a full-wave rectification, and the variable AC voltage is a higher DC voltage, which does not require the transformer to have a center tap. The connection of the four crystal diodes as shown in Figure 3 65 forms a bridge rectifier circuit. Four rectifiers (Zen tubes) connect the input AC and the load together.

When the AC input voltage is positive, the current flows from one side of the input to the other side of the input through a rectifier, a load, and then another rectifier. When the AC input voltage is negative for half a cycle, the current flows through the other pair of rectifiers and loads.

The English name of direct current is direct current, abbreviated as DC. It is embodied in the one-way flow or movement of electric charges. The density of the current changes over time, and the direction in which the current travels through the circuit is usually essentially fixed.

Based on this principle, dc as an adjective is often also used to refer to voltage, for which its polarity never changes.

In a DC circuit, the flow of electrons moves from the cathode, also known as the negative or negative pole, to the anode (positive, positive). Direct current is the movement of electrons from the negative electrode to the positive electrode to form an electric current. Electrochemistry and direct current generated by photoelectric units and batteries.

In many countries, the current coming out of the device is not direct current, but alternating current (AC). Alternating current is converted into direct current by means of a power supply consisting of a special process, such as a converter, a rectifier that prevents the current from moving in the opposite direction, and a filter that eliminates the runout of the current flowing from the rectifier.

In fact, all the electronic products and computer hardware that people use today need direct current to work, but the national grid generally provides 200V standard alternating current. These devices are able to be used normally in life because they convert alternating current into a smaller amount of direct current. The vast majority of solid-state devices require DC voltages that do not exceed the volts range.

Some devices, such as electronic watches and vacuum tubes, directly require current. The current demand of an electronic watch is close to zero, but the wireless communication energy amplifier does require more than 100 amps.

The advantage of direct current is that it requires fewer transmission wires to deliver the same amount of power than alternating current. In addition, when direct current is transmitted, there is no capacitive current, and there is no disadvantage of alternating current due to the additional loss caused by the capacitive current.