盡量希望由天同師兄解答!~
天同兄日前你回答過有關 back e.m.f. http://hk.knowledge.yahoo.com/question/question?qid=7010111301689 既問題,我對最後你的解釋有點不能理解
q:當coil既angular velocity等於V/BAN既時候, current會等於零.
我更加更加五明, 如果佢冇current又點保持住個angular velocity?
你既回答:In an ideal motor, the coil encounters no friction. When the angular speed of the coil w equals to V/BAN, the current reduces to zero (for reason, see answer above). There will not be any net force acting on the coil. But at this moment of time, the coil is rotating with an angular speed. By Newton's First Law, any body, including a body in rotation, will continue its state of rest or uniform motion (uniform rotation in this case). Hence, it is because of inertia that the coil continue rotating under a no net current and no net force condition.
因為我都係同發問果位用同一本書,我睇完你既ans都明你所解答,但如果照你咁講,
個motor冇current都可以郁,power=i V,咁iput power除左starting motor果陣之外咪唔洗再input power?