# Motor and inductor

1. Apr 12, 2007

### momomo_mo

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

2. Apr 12, 2007

### momomo_mo

3. Apr 13, 2007

### lpfr

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.

4. Apr 13, 2007

### Astronuc

Staff Emeritus
In the two examples given:
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

5. Apr 13, 2007

### momomo_mo

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.

6. Apr 13, 2007

### lpfr

You are welcome to post questions. Just try to write them clearly.