Please write the formula for calculating the magnetic field strength.

The calculation formula of magnetic field strength: H = N × I/Le.

Where: h is the magnetic field strength in ampere/meter; N is the number of turns of the excitation coil; I is the excitation current (measured value), in a; Le is the effective magnetic circuit length of the sample, in meters (m)

Calculation formula of magnetic induction intensity: b = φ/(n× AE)

Where: b is the magnetic induction intensity in WB/m2; φ is the induced magnetic flux (measured value), and the unit is WB; N is the number of turns of the induction coil; Ae is the effective cross-sectional area of the sample, and the unit is m * m

Extended data:

Magnetic field strength is a physical quantity that describes the properties of magnetic field. It is expressed by H. Its definition formula is H=B/μ0-M, where b is magnetic induction intensity, m is magnetization intensity, μ0 is magnetic permeability in vacuum, and μ0=4π× 10-7 Weber /(m.an). The unit of H is Ann/meter. In the Gauss system of units, the unit of H is Oster. 1 A/m =4π× 10-3 oster.

In paramagnetic and diamagnetic materials, the formula B=μH holds. As can be seen from the formula, B is directly proportional to H and has the same direction. Under the condition that H has certain symmetry, when there is a medium, H can be obtained by Ampere's loop theorem, and then B can be obtained by the above formula. This method can also be used to approximately calculate H and B in soft ferromagnetic materials. In hard magnetic materials, the directions of H, B and M are generally different, and the relationship between them can only be expressed by the formula H = B/μ 0-M. ..

The ratio of the amount of charge q passing through the cross section of a conductor to the time t taken to pass through these amounts of charge is called current, also called current intensity. I = q/T. If the amount of charge passing through the conductor cross section is 1C within 1s, the current in the conductor is1a..

The microscopic quantity that determines the magnitude of current: Select two sections, B and C, on the conductor AD with uniform thickness of applied voltage. Let the cross-sectional area of the conductor be S, the number of free charges per unit volume of the conductor be N, the charge amount of each charge be E, and the direction movement rate of the charge be V, then all the free charges between two intervals B and C with a distance of vt in time t will be obtained from (I = Δ q/Δ t) through the interval C..I = nesv.

The direction of current is the same as that of positive charge moving in the circuit. Actually, it's not positive charge movement, it's negative charge movement. Electron flow is the movement of electrons (negative charges) in a circuit, and its direction is opposite to that of current. The current intensity can be expressed as:?

Where q is the electric quantity (coulomb) and t is the time (second).

( 1A= 1C/s)？

(ohm's law of partial circuits) or I=E (electromotive force) /(R[ outside ]+r[ inside]) or I=E/(R+Rg[ detector resistance ]+r) (closed-circuit ohm's law) If positive and negative ions move at the same time to form a current, then Q is the sum of two charges.

References:

Baidu Encyclopedia-Magnetic field strength? Baidu Encyclopedia-Current