Simple question about electric motors

[sram]

Hello folks, how is it going?

Most tech people know that if you give an electric motor electricity, it will spin. The opposite is true as well, if you somehow spin the motor(manually for example), it will give you some electricity. Meaning it will work as a generator. Now, if you have two electric motors and you connected their axles together, and you provided one with some voltage it will start spining and make the other motor spin as well since they are connected. If you connected a small bulb to the leads of the second motor, it will light up...........right? See the simple diagram I attached.

Now, here is the question: if you let free the second motor and only hold the first motor in place(The second motor and the small bulb connected to its leads can move freely), the whole motor will spin (Not only the axle)and the bulb will spin with it. While this is happening, the bulb has light with almost the same power as before! Why is this happening ? Is it because the axle of the second motor is spining faster than the motor itself? Shouldn't they be spining at the same speed?????

Hopefully I made myself clear!


Thanks

 

[Gaston]

i would think it is because of what you said. the slipage between the rotor and the housing.

 

[dknguyen]

There is no reason that the motor axle and motor case should be spinning at the same speed- they aren't connected after all, and it's pretty obvious when you watch the motor operating normally since the case just sits there and the shaft spins!

When you say it as spins brightly as before, that is probably with a very weak, very fast motor when slippage is the most. If you try it with a high torque, low speed motor it should be less bright since the motor is able to move it's own case more easily resulting in less slip.

I'm a bit curious how you actually found this out since wouldn't a motor spinning at 20,000 RPM wind up the wires between motor and light bulb really fast?

 

[Roff]

There is no reason that the motor axle and motor case should be spinning at the same speed- they aren't connected after all, and it's pretty obvious when you watch the motor operating normally since the case just sits there and the shaft spins!

When you say it as spins brightly as before, that is probably with a very weak, very fast motor when slippage is the most. If you try it with a high torque, low speed motor it should be less bright since the motor is able to move it's own case more easily resulting in less slip.

I'm a bit curious how you actually found this out since wouldn't a motor spinning at 20,000 RPM wind up the wires between motor and light bulb really fast?

I'm guessing the light bulb also spins.

 

[AllVol]

I'm guessing the light bulb also spins.

I would think he has the bulb connected directly, and closely to the lugs on the motor.

 

[audioguru]

It is difficult to judge the brightness of a light bulb that is spinning around and around. The motor/generator with the light bulb will be unbalanced and the vibration will slow down its case, then its shaft spins much faster than the case so it generates electricity pretty well.

 

[sram]

I'm guessing the light bulb also spins.

The light bulb spins creating a circle of light! It looks cool, that's why i'm doing!

 

[sram]

Any more comments?