hello i found a nice old video which explains the working principle of a DC motor. here you can see the video. i have the basic idea of how a DC motor works. but after watching this video i got a question.
if we refer the below example,
when we apply current. the winding becomes an electromagnet. so if we apply the right hand rule, the AB part becomes the North pole and the CD part becomes the South pole. so similar poles meet each other and they repel each other. due to that the rotation happens. when the winding becomes perpendicular to the permanent magnetic field ( just passing 90 degree angle) it begins to attract to the opposite pole. we can continue the rotation by using two commutator segments and two brushes. in that video at 4:53 he explains it.
but if we refer this example,
where we change the polarity of the voltage and then apply current to the winding. the AB part becomes the South pole and CD part becomes the North pole. so the opposite poles meet each other and they attract each other. in above video he explains it at 4:41. we can clearly see that the winding doesn't rotate.
the first example rotates that's true. but practically if we change the voltage polarity (as the second example) we know that the DC motor should begins to spin in reverse direction. if we apply Fleming's left hand rule we can see that too. but in that video it doesn't happen.
do DC motors work only by repelling and attracting to each poles (as the 1st example)? like when the winding is parallel to the permanent magnetic field, are the poles supposed to be similar (poles of permanent magnet and winding) to make a rotation? thank you.
if we refer the below example,
when we apply current. the winding becomes an electromagnet. so if we apply the right hand rule, the AB part becomes the North pole and the CD part becomes the South pole. so similar poles meet each other and they repel each other. due to that the rotation happens. when the winding becomes perpendicular to the permanent magnetic field ( just passing 90 degree angle) it begins to attract to the opposite pole. we can continue the rotation by using two commutator segments and two brushes. in that video at 4:53 he explains it.
but if we refer this example,
where we change the polarity of the voltage and then apply current to the winding. the AB part becomes the South pole and CD part becomes the North pole. so the opposite poles meet each other and they attract each other. in above video he explains it at 4:41. we can clearly see that the winding doesn't rotate.
the first example rotates that's true. but practically if we change the voltage polarity (as the second example) we know that the DC motor should begins to spin in reverse direction. if we apply Fleming's left hand rule we can see that too. but in that video it doesn't happen.
do DC motors work only by repelling and attracting to each poles (as the 1st example)? like when the winding is parallel to the permanent magnetic field, are the poles supposed to be similar (poles of permanent magnet and winding) to make a rotation? thank you.
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