## The Electric Motor

Video 1 minute:. What is the difference between having permanent magnets and having electromagnets in a DC motor? If the current in the coil were constant, the coil would stop in this position. In practice, a motor also has the permanent magnet curved in a circular shape so it almost touches the coil of wire that rotates inside it.

### Electric motors and generators

So, how does a transformer work? To make a larger emf, use more turns you may need to use finer wire and a frame upon which to wind it. The electric current from the battery connects to the motor's electric terminals. These motors may be called 'universal' motors because they can operate on DC.

## Electric motors

Finally, and again assuming that the transformer is ideal, let's ask what the resistor in the secondary circuit 'looks like' to the primary circuit. What about the commutator? What is Transconductance? Site Navigation. If you are not a member or are having any other problems, please contact customer support.

The emf that a motor generates is called the back emf. We're sorry, this computer has been flagged for suspicious activity. So, when AC current is run through the wire, the electromagnet continues to rotate without stopping. You'll know that two magnets placed near one another either attract or repel. Rotate the coil initially so that the magnetic flux through the coil is zero, as shown in the diagram. Also, the rotation itself causes the contact to be intermittent so, if there are longer bounces during one phase, this asymmetry is sufficient.

Simple Electromagnetic Motor Building high static voltage motor from plastic bottles. This gives several of the advantages of induction motors: In general, for a small motor it is much cheaper to use permanent magnets. Let us know what you have to say: See Drift velocity and Ohm's law. Without transformers, the waste of electric power in distribution networks, already high, would be enormous. Good use of web graphics. The interacting fields then either attract or repel each other to create rotational movement on the output shaft.

Electricity, Magnetism and Electromagnetism. What are fuel cells? This video covers a brushless DC motor where the rotor is on the outside, in other motors the same principle is in reverse, with the electromagnets on the outside. For this reason, some high power several kW domestic devices may require three phase installation.

But that can't happen with our present setup: This is done using the complex phenomena known as induction. They are used in systems that move objects to a precise position, like a scanner, disc drive, and industrial laser carving devices.