Understanding Motor and Inductor Emf

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Discussion Overview

The discussion revolves around the differences in induced electromotive force (emf) in motors and inductors, particularly focusing on the conditions under which emf is generated. Participants explore the mechanisms of induction in these devices and question the scenarios that lead to induced emf.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the process of emf induction in motors and inductors, noting that in motors, the rotation of the coil due to current and magnetic fields leads to a change in magnetic flux and thus induces emf.
  • Another participant questions why there is no induced emf when a coil suddenly stops, suggesting that this situation should resemble that of an inductor where a change in magnetic flux occurs.
  • A later reply clarifies that in motors, the alternating current creates a time-varying magnetic field, while in inductors, the closing of a switch allows for a time-varying current, which is necessary for inducing emf.
  • It is noted that if an inductor is moving in a constant magnetic field, emf will be induced, but if it is stopped, the magnetic field remains constant and no emf is generated.

Areas of Agreement / Disagreement

Participants express differing views on the conditions for induced emf, particularly regarding the scenario of a coil stopping. There is no consensus on the explanation for the absence of induced emf in that case.

Contextual Notes

Some assumptions about the nature of magnetic fields and the conditions for induction remain unresolved, particularly regarding the transition from motion to rest in coils and inductors.

momomo_mo
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In these two cases , emf will be induced in different way.
for motor: current +B-field-->Force-->Coil rotate-->change of magnetic flux-->emf inducedd in the coil
for inductor , when the switch suddenly openfrom closes switch, there are a sudden change of magnetic flux ,there emf will be induced

the thing I want to ask:
why when the coil is suddenly jammed and come to stop,there will not be any induced emf in this cases??
isn't it just the case of inductor,there are a change of magnetic flux
from many to none magnetic flux ?

why?

thank you
 
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HeLPplease
 
Usually people that answer to posted questions, try to write theirs answers clearly and in a correct language without stupid abbreviations, like "u" four "you". I think they deserve that you write your questions clearly, without shortcuts and in a text you could show to your English teacher.
Most people who answer your questions are not your pals. Some of them happen to be older than your actual teachers.
If your post had not been answered, it is not that no one is able to answer. It is just that no one is willing to decode your so badly written question.
 
In the two examples given:
for motor: alternating current +B-field-->Force-->Coil rotate-->change of magnetic flux-->emf inducedd in the coil

for inductor , when the switch suddenly openfrom closes switch, there are a sudden change of magnetic flux ,there emf will be induced
The motor has an applied alternating current, and the time varying current induces a time varying magnetic field (which would otherwise by constant).

In the inductor, the closing of the switch allows a time varying current. A constant current would induced a constant B-field.

If an inductor is moving in a constant magnetic field and emf will be induced. If the inductor is not moving, i.e. stopped, then the field is constant (non-varying) and no emf is induced.

See principle of induction motor - http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/indmot.html

Inductance concepts
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/induct.html
 
SORRY
I think it will be easier for the readers to read my question by using flow chart.I apologized for my poor english because I usually weak in expressing my point of view in English.I used to write in Chinese.Really sorry.Sorry for all the readers.Sorry for my distrubance.
 
You are welcome to post questions. Just try to write them clearly.
 

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