# What's inside a dc motor+explanation

Apparatus: 1 Small Screwdriver
1 Small 3-5v dc motor

How does a dc-motor work?
As you saw in the video,we found a mini metal rod on which copper wire was coiled.This part is called the ARMATURE​:point_down:

On the top of this armature there are 3 conductive metal plates which are connected to the copper winding on the armature.So, that
whenever supplied with current the armature turns into a electro magnet and is rotated by the ferrite magnets present in the metal case

Now,how do we supply the armature with current?

We,also found one plastic part from the front of the motor which had mini copper plates turned in such a way that it touches the conductive plates even when armature is rotating.This plastic part has 2 terminals on which we can attach a battery and the motor will start rotating.Here’s a picture for more clarification​:point_down:

Thanks for reading till the end!!!

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Interesting!!
What will happen if we reverse the polarity of the supply?

What would happen if, instead of supplying electric current, we rotate it using external force? Will it produce electricity?

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Yes, if we rotate the shaft or the armature it will produce electricity.This small motor can only produce 1-2v on high speed.The amount of voltage generated depends on the size,type and speed of the motor.

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@Abhinav7996 if we change the polarity of the dc motor, the direction of its motion is reversed. Does it happen in an AC motor too?

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Yes,if we switch the switch the wires of a ac motor then it’s shaft will also move in the opposite direction just like a dc motor because the magnetic fields change.

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Let’s try it.
It will be interesting to note if we have a spare table fan or a pedestal fan.
Just try to switch the wires from positive to negative and vice versa and share your observations.

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Surely,I will try it using a spare exhaust fan

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https://metastudio.org/t/1-share-your-questions/4766/5?u=pritika

You can also try it to prove my point.

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Yeah Sure!
Thanks for the suggestion

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I think If we rotate The polarity , It will Change The direction Of rotation

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@singh @NAVTEJ7939 I tried it on a exhaust fan which is an AC motor and the results were very surprising. When I switched the wires the motor did not change the direction of rotation which was completely ironical. According to my research, I found out that a AC motor will also change it’s direction of rotation but I never tried it.
Conclusion: An AC motor will not change it’s direction of rotation if we change the polarity of the supply but it is completely opposite in the case of dc motors.

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Is this motor Brushless or Brushed

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When I switched the wires the [AC] motor did not change the direction of rotation which was completely ironical. According to my research, I found out that a AC motor will also change it’s direction of rotation. … An AC motor will not change it’s direction of rotation if we change the polarity of the supply

When do you say a point is positive with respect to the other point? Alternating means sometimes point A is positive sometimes it is negative. In AC the voltage difference is described by a Sine function.

What is the Phase and Neutral in household AC electric circuit? Positive and Negative?

The exhaust fan is a single phase motor. Have you seen a capacitor with it? Suppose A and B are the points on the two wires connected to the capacitor. Reverse this connection. Find whether the fan will rotate in the opposite direction? Anyone, unable to experiment physically, with thought experiment / prediction please?

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It was a Brushed Ac Motor

@kvk you’re entirely correct. Tried it by reversing the connections of the capacitor but as you said in alternating current (Ac) sometimes A will be positive sometimes b will be positive so it doesn’t really matter if we reverse the connections and obviously the motor didn’t change the direction of rotation.

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