Science Buddies: "Ask an Expert"

My daughter is making the electric motor using a D 2 battery and the paper clips and magnetic wire in a coil. She sanded one end completely and left the other end half sanded. I want to make sure I understand some of these concepts from reading the background information before talking more to her about the project.
1. The wire is not sanded completely on one end to result in a stop/start electrical flow. Correct???
2. The wire that is only half sanded should be on the paperclip attached to the positive terminal of the battery because the electricity flows from positive to negative and that is where we need to get our stop/start of the current to keep the coil spinning. Correct??
3. The North pole always pushes up and the south pole always pushes down on the magnet that is under the wire? Yes?
4. The magnet is exerting an upward/downward force on the wire because the wire is magnetic. Why though? The magnet is really pushing against itself? and the wire is caught up in this struggle or yeah because the magnet is pushing against its own poles within itself you get the up and down force on the wire?
5. Does the electrical force that is going through the wire travel from the positive terminal to negative terminal via the coil and back again in a continual loop that goes back and forth or is it unidirectional from positive to negative and stops?

Thank you
Mandy

[Administrator note: project: https://www.sciencebuddies.org/science- ... tric-motor]

Hi Mandy,

This looks like a fun project and a great way to understand more about how electric motors work.

1. The half sanded part of the wire acts as a switch to stop the current flow during half of the coil rotation. Without this “switch” the coil would oscillate back and forth instead of rotating. This is explained in more detail here:

https://www.explainthatstuff.com/electricmotors.html

2. The half sanded end of the wire coil can be attached to either battery terminal. The half sanded wire will act as a switch as described above regardless of the battery orientation.

3. The magnet (under the wire) has two poles. The magnetic field from the magnet is perpendicular to the wire coil.

4. The wire has a magnetic field around it due to the current flowing through the wire. The coil moves because the force from the permanent magnetic field “pushes” the wire's magnetic field.

5. The current flows from the battery positive through the wire and back to the battery negative terminal.

You may find the Electricity, Magnetism and Electromagnetism Tutorial useful:

https://www.sciencebuddies.org/science- ... m-tutorial

I hope this helps. Please ask again if you have more questions.

A. Norman