Direct current in electric motors?

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Plasm47
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1. Small electric motors with only one armature loop sometimes get stuck. They can be started again by giving the armature a small twist. Looking at the diagram below, what might be the explanation for the motor not being able to start on its own?
Diagram of a single-loop DC motor in a circuit with a battery, marked +ve and -ve, and an arrow labelled current flow; the loop sits at the top with dots and crosses showing current direction, and two solenoids with batteries appear at the sides.


When the brush(es) reaches the split within the ring, current ceases to flow. This lack of electricty will stop the split ring commutator and evidently, the motor. Since no current can be transmitted, the motor can't start on its own. However, giving the armature a small twist will close the circuit allowing the motor to operate.

Please help! I'm not really understanding the principles of motors. I'm taking shots in the dark in answering my questions.
 
Last edited:
Plasm47 said:
1. Small electric motors with only one armature loop sometimes get stuck. They can be started again by giving the armature a small twist. Looking at the diagram below, what might be the explanation for the motor not being able to start on its own?
Circuit diagram of a DC motor with a battery marked +ve and -ve, current flow arrow up the left side, and a coil between brushes with arrows showing rotation.


When the brush(es) reaches the split within the ring, current ceases to flow. This lack of electricty will stop the split ring commutator and evidently, the motor. Since no current can be transmitted, the motor can't start on its own. However, giving the armature a small twist will close the circuit allowing the motor to operate.

Please help! I'm not really understanding the principles of motors. I'm taking shots in the dark in answering my questions.

Your answer is fine. Can you think of some things that could be done to minimize this problem with DC brushed motors?
 
berkeman said:
Your answer is fine. Can you think of some things that could be done to minimize this problem with DC brushed motors?

The problem can be minimize by using more than one armature
 
Plasm47 said:
The problem can be minimize by using more than one armature

Good answer! :smile: