Open Classification: Science, Physics, Circuit, Electricity, Current
Catalogue
? The microscopic expression of current
? Basic calculation formula of current
? Direction of current
? Why does the current form
? Conditions for current generation
? Unit of current-ampere
? Measurement of current-ammeter
? Three major effects of current < P > Current refers to the directional movement of charge. The magnitude of current is called current intensity (I for short), which refers to the amount of charge passing through a certain section of a conductor in unit time, and the amount of electricity passing through one coulomb per second is called an ampere (A). Ampere is the basic unit of all electricity in the international system of units. Besides A, the commonly used units are milliampere (mA) and microampere (μ a) < P > 1A = 1 mA = 1 μ a < P > The microscopic expression of current
I = nesv. Where n represents the number of free charges per unit volume, e is the amount of electrons, s is the cross-sectional area of the conductor, and v is the directional movement rate of free electrons.
basic calculation formula of current
I=C/T=U/R
The direction of current
It is physically specified that the direction of current is the direction of positron flow or the opposite direction of negative electron flow
In general, electrons refer to negative electrons, unless it is specified that the reason for the formation of positron
current
Voltage is to make the charge in the circuit move directionally.
2. There is a voltage across the conductor (a power supply is necessary to obtain a continuous current in the closed loop).
the unit of current-ampere
the current unit ampere is abbreviated as ampere, and its symbol is: a. It is defined as: ampere is a constant current. If it is kept in two infinite parallel straight wires with a negligible circular cross-section in a vacuum, the force generated between the two wires is equal to 2×1-7 Newton per meter. This definition was approved at the Ninth International Metrology Congress in 1948, and ampere was formally adopted as one of the basic units of the international system of units at the 11th International Metrology Congress in 196.
Measurement of current-ammeter
What are the requirements when using ammeter
1. Symbol of ammeter: -A-
Usage of ammeter
1. Ammeter should be connected in series in the circuit
2. Connection of positive and negative terminals should be correct: current flows in from positive terminals, Flowing from the negative terminal.
3. The measured current should not exceed the range of the ammeter.
4. It is absolutely forbidden to connect the ammeter directly to the two poles of the power supply without using electrical appliances.
5. Confirm the range of the ammeter currently in use.
6. Confirm the current value represented by each large cell and each small cell.
Try to touch it first, and solve problems first. <
(3) The pointer deflects slightly,
(4) The pointer deflects reversely.
Three major effects of current
1 Thermal effect
2 mAgnetic effect
3 Chemical effect
Question 2: What is the standard unit of current? It is ampere, and the derivative units of symbol A are milliampere (Ma) and microampere (P). The commonly used units are milliampere (mA)/microampere (uA), and the conversion rule of current unit is: 1A = 1 MA = 1, μ A. The international unit of electric power is Watt, and the symbol is W. Commonly used units are kilowatts (KW)/MW (MW < P > Question 3: What is the current unit of CA? CA-is the issuing institution of certificates, and it is the core of PKI. CA is the authority responsible for issuing certificates, authenticating certificates and managing issued certificates. It should formulate policies and specific steps to verify and identify the user's identity and sign the user's certificate to ensure the identity of the certificate holder and the ownership of the public key.
You can look it up on Baidu. `
Question 4: What is the current unit ω _ Chinese ohm is the unit of resistance, not the unit of current.
1ω = 1V/1A
Question 5: What is the unit of current? Current refers to the directional movement of charge. The magnitude of current is called current intensity (I for short), which refers to the amount of charge passing through a certain section of a conductor in unit time, and the amount of electricity passing through one coulomb per second is called an ampere (A). Ampere is the basic unit of all electricity in the international system of units. Formula and formula of unit current intensity: where q is electric quantity (coulomb, unit c) and t is time, in seconds (s). The following formula shows that one coulomb of electricity passing through a certain section of a wire in one second is one ampere. In addition to A, the commonly used units are milliampere (mA) and microampere (μA), which are converted into the microscopic expression of 1A = 1 mA = 1 μ A < P > current: I = nesv. Where n represents the number of free charges per unit volume, e is the amount of electrons, s is the cross-sectional area of the conductor, and v is the directional movement rate of free electrons.
direction of current
It is physically stipulated that the direction of current is the direction of positron flow or the opposite direction of negative electron flow
In general, electrons refer to negative electrons, unless it is specified that they are positrons
Question 6: What do Na and Pa represent in the current unit? You answered yourself, nA is nanoampere equal to .1 microampere, and pA picoampere is .1 microampere
Question 7: The unit of rated current. The unit of current is ampere. Rated current is the current value that can be used for a long time by electrical equipment, and the unit is also ampere.
question 8: what are the units of current and how to convert them? 1. the international unit of current is ampere (a).
2. commonly used units are: kiloampere (KA), ampere (a), milliampere (mA) and microampere (uA). The unit that is not commonly used is Pian pA.
3. Scope of application:
Electric power system, commonly used ampere (A) and kiloampere (KA).
commercial power, commonly used in power supply, ampere (a) and milliampere (mA).
mA and uA are commonly used in control circuits.
Pian pA is usually used in the laboratory.
4. unit conversion: the unit conversion of current is in thousands.
1KA=1A；
1A=1mA；
1mA=1uA；
1uA=1pA。
question 9: what is the unit of measurement of a (ampere) in current? It is the unit of current ampere! It's short for ampere! Usually represented by the letter I! It means that the physical quantity Gong conversion unit of current is
1mA (milliampere) =-1A 1 microampere =-1A.