Inductance: When a coil of current is passed through it, a magnetic field is induced in the coil, and the induced magnetic field in turn produces an induced current to resist the current passing through the coil. This interaction between the current and the coil is called the inductive reactance of electricity, or inductance.
Capacitance: The ratio of the amount of electricity carried by a capacitor, Q, to the voltage, U, between the poles of the capacitor is called the capacitance of the capacitor. In electrical circuits, the ability of a capacitor to store charge, given a potential difference, is called capacitance, labeled C.
1. Inductance includes self-inductance and mutual inductance:
Self-inductance: When a current is passed through a coil, a magnetic field is generated around the coil. When the current in the coil changes, the magnetic field around it also produce corresponding changes, this change in the magnetic field can make the coil itself produces induced electromotive force (induced electromotive force) (electromotive force used to indicate the end voltage of the ideal power supply of the active component), which is the self-inductance.
Mutual inductance: two inductive coils close to each other, an inductive coil of the magnetic field changes will affect the other inductive coil, this effect is mutual inductance. The size of the mutual inductance depends on the self-inductance of the inductor coil and the degree of coupling of the two inductor coils, the use of this principle made of components called mutual inductors.
2, capacitance
Capacitance is the ability to accommodate an electric field. Any electrostatic field is composed of many capacitors, there is an electrostatic field there is capacitance, capacitance is described by the electrostatic field. It is generally accepted that an isolated conductor and infinity constitute a capacitance, and a conductor grounded is equivalent to being received at infinity and connected to the earth as a whole.
Expanded information:
Calculation of inductance and capacitance:
1, the calculation of inductance:
(1) self-inductance
A coil (or coil of wire) with a current of I is connected to the earth. A coil (or loop) with a current I, the sum of the fluxes interchained by its turns is called the magnetic chain of the coil ψ. If the fluxes interchained by the turns are Φ, and the number of turns of the coil is N, then the magnetic chain of the coil ψ = N Φ. When the coil current I varies in time, the magnetic chain Ψ varies in time as well. According to the law of electromagnetic induction, a self-inductive electromotive force EL will be induced in the coil with a value of
Define the self-inductance L of the coil as the ratio of the self-inductive electromotive force eL and the time derivative of the current, dI/dt, with a negative sign, i.e.
In the above two equations, the positive directions of ψ and eL, and ψ and I are in accordance with the rule of the right-hand spiral. Knowing the inductance L, the self-inductance electromotive force can be calculated from dI/dt. In addition, self-inductance can be defined as follows
(2) Mutual inductance
Let there be two adjacent coils in a linear magnetic medium. There is a current I1 in coil 1, and the portion of the magnetic flux generated by I1 that is interchained with coil 2 forms a mutually inductive magnetic chain ψ21. As the current I1 varies with time, so does ψ21; by the law of electromagnetic induction, there will be a mutually inductive electromotive force M2 in coil 2
Define the mutual inductance M21 of coil 1 to coil 2 to be
or
Similarly, if there is a current in coil 2 I2, it produces a mutual inductance magnetic chain ψ12 interchained with coil 1. when I2 varies, a mutual inductance electromotive force EM1 occurs in coil 1
Equation M12 is called the mutual inductance of coil 2 to coil 1. The above equation is the defining equation of M12.
If the current I1 is a constant current, or I1 is a time-varying current with a low rate of change, the mutual inductance magnetic chain ψ12 is proportional to I1, and this proportionality coefficient (a positive constant) is the mutual inductance of coil 1 to coil 2, M21, and
ψ21=M21I1
Similarly, if the current I2 is a constant current, or a time-varying current with a low rate of change, ψ2 is proportional to I2 The coefficient of proportionality is the mutual inductance M12 of coil 2 to coil 1, and
ψ12=M12I2
Theoretically proved that M12=M21, with M representing them, then
In coil 1, 2 at the same time through the time-varying current, they are I1, I2, respectively, the induced electromotive force in the coil, e1, e2, is the sum of the self-induced electromotive force and the mutual electromotive force
Similarly, if current I2 is constant or low rate of change, ψ2 and I2 are proportional to each other. p>
2, capacitance calculation:
Definition: C = Q / U
Determination: C = εS/4πkd?
Where ε is a constant, S is the area directly opposite the capacitor plate, d is the distance of the capacitor plate, k is the electrostatic force constant.
Capacitor potential energy formula: E = CU^2/2 = QU/2 = Q^2/2C
Multiple capacitors in parallel formula: C = C1 + C2 + C3 + ... + Cn
Multiple capacitors in series formula: 1 / C = 1 / C1 + 1 / C2 + ...+ 1/Cn
Three capacitors in series: C=(C1*C2*C3)/(C1*C2+C2*C3+C1*C3)
Baidu Encyclopedia - Inductors
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