Back EMF (electromagnetic induction)

  • Thread starter v_pino
  • Start date
169
0

Main Question or Discussion Point

1)When the current through the coil of a motor flows it cases the coil to spin.
2)The spinning motion causes the wires in the coil to cut through the magnetic field.
3)The current induced (back EMF) in the wires by this spinning motion opposes the change that causes it. (Lenz's Law)
4)Current supplied against this EMF requires electrical energy.
5)It is this energy that is converted to the kinetic energy of the motor.

I don't understand 4) and 5). Where does this electrical energy come from? I thought the motor's kinetic energy comes the the initial electrical current supplied to it...

Thanks.
 

Answers and Replies

I am a bit confused too but I think that:
Whenever a current carrying coil is put in a magnetic field, a torque acts on it. This is responsible for its rotational motion and forms the working principle of galvanometers.
But this rotational motion causes the induction of opposing emf and this tends to resist the rotation. So to keep up the same rotation rate more energy needs to be supplied. So it is this energy which gives the motor its kinetic energy.
 
634
1
1)When the current through the coil of a motor flows it cases the coil to spin.
2)The spinning motion causes the wires in the coil to cut through the magnetic field.
3)The current induced (back EMF) in the wires by this spinning motion opposes the change that causes it. (Lenz's Law)
4)Current supplied against this EMF requires electrical energy.
5)It is this energy that is converted to the kinetic energy of the motor.

I don't understand 4) and 5). Where does this electrical energy come from? I thought the motor's kinetic energy comes the the initial electrical current supplied to it...

Thanks.
The energy comes from the Battery or the power supply supplying the motor. The back emf generated is very small compared to the source emf.
 

Related Threads for: Back EMF (electromagnetic induction)

  • Last Post
Replies
10
Views
2K
  • Last Post
Replies
10
Views
3K
  • Last Post
Replies
2
Views
2K
Replies
1
Views
902
  • Last Post
Replies
6
Views
878
  • Last Post
Replies
11
Views
3K
  • Last Post
Replies
16
Views
4K
  • Last Post
Replies
1
Views
1K
Top