The magnetic field generated by the closed circuit in the original magnetic field blocks the original magnetic fieldMagnetic fluxThe changing current is called induced current.
It refers to theconductorIf it is closed into a circuit, the electromotive force will drive the electrons to flow and form an induced current (induced current).
Generally speaking, when a part of the conductor in the closed circuit is operating in the magnetic fieldCutting magnetic induction line movementThe magnetic flux in this closed loop must change whenClosed loopThe induced electromotive force (EMF) is generated in the, resulting in current, which is called induced current.
In 1831, British physicistFaradayElectromagnetic induction phenomenon is found, namely“Magnetoelectricity”The generated current is called induced current.
Conditions
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As long as theMagnetic fluxWhen a change occurs, an induced current will be generated in the closed circuit.Therefore“Closed circuitPart ofconductorIn the magnetic induction lineCutting magnetic induction line movementThe generated current is called induced current "which is one-sided. The conductor can also generate induced current without cutting the magnetic induction line.
Direction judgment
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Judgment method: useRight-handed rule, that is, extend the right hand so that the thumb is perpendicular to the other four fingers and in the same plane with the palm of the hand;Let the magnetic induction wire enter from the palm of the hand, and make the thumb point to the direction of the wire movement. At this time, the direction of the four fingers is the direction of the induced current.
The direction of coil rotation and magnetic field affect the direction of induced current.
electromagneticsThe right hand rule mainly judges the direction irrelevant to the force.
It can also be based onLenz's law, the direction of the magnetic field generated by the induced current blocks the change of the original magnetic field, and reuseRight hand spiral ruleDetermine the direction of the current in the coil.
When the conductor is stationary in the magnetic field or moves parallel to the magnetic induction line, the magnetic flux does not change, so no matter how strong the magnetic field is, there is no induced current in the closed circuit.
The magnitude of induced current and magnetic induction B, the length of conductor LMovement speedv，And the sine of the included angle θ between the moving direction and the direction of the magnetic induction line is proportional.Increase magnetic induction B, increaseCutting magnetic induction lineThe induced current can be increased by increasing the cutting speed v and cutting the magnetic induction line as vertically as possible (θ=90 °).
Note: In theory, the higher the cutting speed, the better. However, due to the large inertia of the meter pointer (especially large demonstration meters), when the cutting speed is too high, the pointer has no time to respond, so the induced current displayed by the meter decreases instead.So.Attention should be paid to selecting appropriate cutting speed to achieve better demonstration effect.
