dc motor的疑問!

guaeiogaeighi

2010-08-07 9:45 pm

疑問 1. 點解when the motor is switched on, w(o me ga)會一路升?
疑問 2. a)點解torque變,w(o me ga)就stable? b) 點解無torque,w( o me ga)就唔再升?
疑問 3. 當net torque=0,coil仲會唔會轉?
疑問 4.點解net torque=0,w( o me ga) is stable,不會再升?
疑問 5.點解要有個stable既w(o me ga)?
疑問 6. ac motor係咻用permanant magnet?

回答 (1)

天同

2010-08-10 10:18 pm

✔ 最佳答案

1. This is apparent. The coil rotates because a torque is produced by the current flowing in the coil in a magnetic field.

2. (a) you need to give how the torque changes.
(b) This is again apparent. No net torque gives no acceleration.

3. Yes. If the coil is rotating, it will rotate at constant speed when the net torque is zero.

4. This is same as 2(b)

5. This is the purpose of using a motor, for example the motor in an eelctric fan.

6. Permanent magents are only used in small motors, e.g. those used in small electrical appliances. Most industrial ac motors use electromagent.

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