How to calculate the electromagnetic induction force

1. A part of the conctor of a closed circuit cuts the magnetic inction line in the magnetic field, and the current will be generated in the conctor. This phenomenon is called electromagnetic inction. The current proced is called inced current. Electromagnetic inction, also known as magnetoelectric inction phenomenon, refers to the conctor placed in the changing magnetic flux, which will proce electromotive force. This electromotive force is called inced electromotive force or inced electromotive force. If the conctor is closed into a loop, the electromotive force will drive electrons to flow and form inced current (inced current)[ Cutting magnetic inction line movement: the so-called cutting magnetic inction line movement refers to the movement of the object in the magnetic field, and the movement has partial velocity in the direction perpendicular to the magnetic inction line If the closed circuit is a coil with n turns, the calculation formula can be expressed as follows: where n is the number of coil turns, Δ Is the variation of magnetic flux, in WB, Δ T is the time taken to change, unit: s ε Is the inced electromotive force generated, in V. 1. Calculation formula of inced electromotive force 1) e = n ΔΦ/Δ T (universal formula) {Faraday's law of electromagnetic inction, e: inced electromotive force (V), N: number of turns of inction coil, ΔΦ/Δ t: The change rate of magnetic flux} 2) e = blvsina (cutting magnetic inction line motion) e = V and l in BLV can not be parallel to the magnetic inction line, but can not be perpendicular to the magnetic inction line, where sina is the angle between V or L and the magnetic inction line 50: Effective length (m)} 3) em = nbs ω Maximum inced electromotive force of alternator {em: peak value of inced electromotive force} 4) e = BLL ω/ 2 (one end of the conctor is fixed to ω Rotary cutting) ω: Angular velocity (rad / s), V: velocity (M / s)} 2 Φ＝ BS { Φ: Magnetic flux (WB), B: magnetic inction of uniform magnetic field (T), s: opposite area (M2)} I picked them up from the Internet. You can see for yourself. I haven't learned them yet. I can only collect data for you

2.

The formula of magnetic inction is b = f / IL = f / QV = E / v= Φ/ S

in the magnetic field, the ampere force on the concting wire perpendicular to the direction of the magnetic field is f, the current is I, and the length of the concting wire is L

the charge quantity is Q, the velocity is V, the electric field intensity is e, and the magnetic flux is v Φ， S is the area

note:

1. The magnitude and direction of the magnetic inction intensity at a certain position in the magnetic field exist objectively, which has nothing to do with the current of the wire and the length of the wire. So we can't say that B is inversely proportional to the proct of f or B

2. In the same magnetic field, no matter how the current I and length l change, the ratio of the proct of magnetic force F and IL is constant. But in different positions, it is generally different

< H2 > the indirect measurement method of magnetic inction intensity based on extended data

1

when a conctor is placed in a uniform magnetic field in the x-axis direction and there is a current in the y-axis direction, there is a potential difference between the upper and lower sides of the conctor. This phenomenon is called Hall effect. Using the principle of Hall effect, a magnetometer can be made to measure the magnetic inction

The magnetic inction was measured by dynamic method

According to Newton's law of motion, the dynamic equation is established to calculate the magnetic inction intensity

The magnetic inction was measured by sensors

sensor is a kind of component that converts non electrical physical quantities, such as displacement, acceleration, pressure, temperature, flow rate rise, light intensity, etc., into electrical quantities, such as voltage and current, etc

A basic idea of the application of

sensors is the idea of transformation, that is, using sensors to convert some physical quantities that are difficult to measure directly into electrical quantities that are relatively easy to measure

3.

Magnetic inction: B = f / IL = f / QV= Φ/ S

F: Lorentz force or ampere force

Q: charge quantity

V: velocity

e: electric field intensity

Φ=Δ BS or B Δ S. B is the magnetic inction, s is the magnetic flux

s: area

L: length of conctor in magnetic field

in the international system of units (SI), the unit of magnetic inction is Tesla (T). In the Gauss unit system, the unit of magnetic inction is Gauss (GS). 1t = 10kgs is equal to the fourth power Gauss of 10. Due to historical reasons, the basic physical quantity describing the magnetic field corresponding to the electric field strength e is called magnetic inction strength B, while the other auxiliary quantity is called magnetic field strength h, which is easily confused

extended data

the direction of the magnetic field is the direction of the magnetic inction intensity. The judgment method is to put in the direction of the magnetic force on the north pole of the small magnetic needle, which is also the direction when the small magnetic needle is in stable balance

the direction of Ampere force on the electrified conctor can be determined by the left hand rule: let the magnetic inction line pass through the palm of the left hand vertically, four fingers point to the direction of current, and make the thumb and four fingers vertical. The direction of thumb refers to the direction of magnetic field force (ampere force) on the electrified conctor. If the magnetic inction line is not perpendicular to the current direction, the magnetic inction intensity is decomposed into perpendicular to the current direction and parallel to the current direction. For the component perpendicular to the current, the above left-handed rule can be applied. If it is parallel, it is not subject to ampere force

It can be seen that ampere force is perpendicular to the plane determined by magnetic inction and current. Currents in the same direction attract each other, while currents in the opposite direction repel each other

note: the magnetic inction intensity B of a certain point in the magnetic field is objective and has nothing to do with whether to place an electrified wire. In the definition formula F = bil, it is required that a small section of electrified wire should be placed perpendicular to the magnetic field. If it is placed parallel to the magnetic field, the force F is zero

4. In the electromagnetic inction phenomenon, an inced current is generated in the conctor, and the current is affected by the ampere force in the magnetic field, so the ampere force is applied to the current by the original magnetic field, and the original magnetic inction intensity is used.

5.

All formulas of electric field and magnetic field in high school physics:

1. Magnetic inction intensity is a physical quantity used to express the strength and direction of magnetic field, which is a vector, unit: T), 1t = 1n / am

< P > 2. Ampere force F = bil Note: l ⊥ b) {B: magnetic inction (T), F: Ampere force (f), I: current intensity (a), l: conctor length (m)}

3. Lorentz force F = QVB (note V ⊥ b); Mass spectrometer {F: Lorentz force (n), Q: charged particle charge (c), V: charged particle velocity (M / s)}

4. In the case of ignoring gravity (without considering gravity), the movement of charged particles into the magnetic field (master two kinds):

(1) charged particles enter the magnetic field along the direction parallel to the magnetic field: not affected by Lorentz force, Do uniform linear motion v = V0

(2) charged particles enter the magnetic field along the direction perpendicular to the magnetic field: do uniform circular motion, the rule is as follows: a) f direction = flo = MV2 / r = M ω 2r=mr(2 π/ T)2=qVB; r=mV/qB; T=2 π m/qB;( b) The period of motion has nothing to do with the radius and linear velocity of circular motion, and Lorentz force does no work on charged particles (in any case)

[calculation formula of inced electromotive force]:

1) e = n ΔΦ/Δ T (universal formula) {Faraday's law of electromagnetic inction, e: inced electromotive force (V), N: number of turns of inction coil, ΔΦ/Δ t: Change rate of magnetic flux}

2) e = BLV vertical (cutting magnetic inction line motion) {L: effective length (m)}

3) em = nbs ω( Maximum inced electromotive force of alternator) {em: peak value of inced electromotive force}

4) e = BL2 ω/ 2 (one end of the conctor is fixed to ω (rotary cutting){ ω: Angular velocity (rad / s), V: velocity (M / s)}

2 Φ= BS { Φ: Magnetic flux (WB), B: magnetic inction intensity of uniform magnetic field (T), s: opposite area (M2)}

3. The positive and negative poles of inced electromotive force can be determined by the direction of inced current {current direction inside the power supply: from negative to positive}

note: (1) the direction of inced current can be determined by Lenz's law or right-hand rule, and the application points of Lenz's law

(2) the self inced current always hinders the change of the current which causes the self inced electromotive force

(3) unit conversion: 1H = 103mh = 106 μ H

(4) other related contents: self inction / fluorescent lamp

Voltage instantaneous value E = EMSin ω Instantaneous value of tcurrent I = imsin ω t;( ω= two π f)

2. EMF peak EM = NBS ω= 2blv current peak value (in pure resistance circuit) Im = EM / R total

3; U=Um/(2)1/2 ; I = im / (2) 1 / 2

4; I1/I2=n2/n2; In the long-distance transmission, using high-voltage power transmission can rece the loss of power on the transmission line, and the loss ′ = (P / U) 2R

(P loss ′: power lost on the transmission line, P: total power transmitted, u: transmission voltage, R: resistance of the transmission line)

The physical quantities and units in Formula 1, 2, 3 and 4 are as follows ω: Angular frequency (rad / s); t: Time (s); n: Coil turns; B: Magnetic inction intensity (T)

s: area of coil (M2); U output voltage (V); 1: Current intensity (a); P: Power (W)

expand data:

accumulation is the work after memory in the process of learning physics. On the basis of memory, we constantly collect a lot of information about physics knowledge from textbooks and reference materials. Some of the information comes from a question, some from an illustration of a question, and some from a short reading material. In the process of collecting and sorting out, we should be good at analyzing and classifying different knowledge points. In the process of sorting out, we should find out the similarities and differences, so as to remember them

The process of accumulation is a process of struggle between memory and forgetting, but it is necessary to make the knowledge more comprehensive and systematic through repeated memory, and make the formula, theorem and law more closely linked, so as to achieve the purpose of accumulation. It must not be like repeated labor like a bear breaking a stick, mechanically memorizing without thinking, and the result can only make the memory more than forgetting

6.

The phenomenon of electromagnetic inction is one of the most important discoveries in electromagnetics. It shows the mutual connection and transformation between electric and magnetic phenomena. The deep study of its essence reveals the connection between electric and magnetic fields, which is of great significance to the establishment of Maxwell's electromagnetic field theory
if the closed circuit is an n-turn coil, it can also be expressed as: ε= n( ΔΦ/Δ t) Where n is the number of coil turns, ΔΦ Is the variation of magnetic flux, in WB, Δ T is the time taken to change, unit: s ε The basic formula of the law of electromagnetic inction is e = - n (d) Φ)/( In this way, we can not justify ourselves on the phase plane
(1) the expression in time domain is e (T) = - n (d) Φ)/( (2) in the complex frequency domain, the expression is e = - jwn Φ， The bold representation vector
(3) if we only look at the size | e | = n | - (d) Φ)/( DT) | [calculation formula of inced electromotive force] 1) e = - n* ΔΦ/Δ T (universal formula) {Faraday's law of electromagnetic inction, e: inced electromotive force (V), N: number of turns of inction coil, ΔΦ/Δ T flux change rate}
2) e = - blvsina (cutting magnetic inction line motion) e = V and l in BLV can not be parallel to the magnetic inction line, but can not be perpendicular to the magnetic inction line, where angle a is the angle between V or L and the magnetic inction line{ 50: Effective length (m)}
3) em = nbs ω Maximum inced electromotive force of alternator) {em: peak value of inced electromotive force}
4) e = - B (L ^ 2) ω/ 2 (one end of the conctor is fixed to ω (rotary cutting){ ω： Angular velocity (rad / s), V: velocity (M / s)}
2 Φ= BS { Φ： Magnetic flux (WB), B: magnetic inction intensity of uniform magnetic field (T), s: opposite area (M2)}
3. The positive and negative poles of inced electromotive force can be determined by the direction of inced current {current direction inside the power supply: from negative to positive}
* 4. Self inced electromotive force E = - n* ΔΦ/Δ t=L Δ I/ Δ T {L: self inctance coefficient (H) (coil L with iron core is larger than that without iron core), Δ 1: Changing current, Δ t: Time taken, Δ I/ Δ t: Change rate of self inced current (change speed)}

7. Electromagnetic inction (EI) phenomenon refers to the conctor placed in the variable magnetic flux, which will proce electromotive force. This electromotive force is called inced electromotive force or inced electromotive force. If the conctor is closed into a loop, the electromotive force will drive electrons to flow and form an inced current (inced current)
. [calculation formula of inced electromotive force] 1) e = n ΔΦ/Δ T (universal formula) {Faraday's law of electromagnetic inction, e: inced electromotive force (V), N: number of turns of inction coil, ΔΦ/Δ t: The change rate of magnetic flux}. 2) E = blvsina (cutting magnetic inction line motion) V and l in E = BLV can not be parallel to the magnetic inction line, but can not be perpendicular to the magnetic inction line, where sina is the angle between V or L and the magnetic inction line{ 50: Effective length (m)} 3) em = nbs ω The maximum inced electromotive force of alternator {em: peak value of inced electromotive force}. Hand held electromagnetic inction
4) e = B (L ^ 2) ω/ 2 (one end of the conctor is fixed to ω (rotary cutting){ ω： Angular velocity (rad / s), V: velocity (M / s), (L ^ 2) refers to the square of L}. 2. Magnetic flux Φ= BS { Φ： Magnetic flux (WB), B: magnetic inction of uniform magnetic field (T), s: opposite area (M2)} calculation formula △ Φ=Φ 1- Φ 2 ，△ Φ= B△S=BLV△t 3. The positive and negative poles of the inced electromotive force can use the inced current direction to determine {the current direction inside the power supply: from the negative to the positive}. 4. Self inced electromotive force E = n ΔΦ/Δ t=L Δ I/ Δ T {L: self inctance coefficient (H) (coil L with iron core is larger than that without iron core), Δ 1: Change current,? t: Time taken, Δ I/ Δ t: Suzhou Fulin electromagnetic heating equipment factory is an enterprise procing electromagnetic inction.

8. B=F/ILSIN α， among α It is the angle between the conctor and the direction of the magnetic field, and the unit of magnetic inction intensity is Tesla.
in the problem of electrified conctor, first calculate the ampere force on the electrified conctor, then use the formula B = f / ilsin α， Calculate B,
in the problem of charge moving in the magnetic field, first find the center of the circle, then calculate the radius, and then calculate the radius according to bqv = MV & # 178/ r. Then we can get the magnetic field B

9. If the circuit is closed, there will be current,
the current interacts with the magnetic field. There is ampere force,
according to Lenz's law, it will prevent electromagnetic inction, which is resistance.

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