Magnetism and Electromagnetism Fundamentals
Ever wondered why your headphones work or how electric motors spin? It all comes down to the fascinating relationship between electricity and magnetism. When electric current flows through a wire, it creates a magnetic field around it - this is the foundation of electromagnetism.
Permanent magnets keep their magnetism all the time and have north and south poles that either attract or repel each other. Induced magnets only become magnetic when placed near another magnet. The magnetic field is strongest at the poles and gets weaker as you move away.
You can make electromagnets stronger in several ways: use a larger current, add more turns of wire, put the turns closer together, or stick an iron core in the middle. Solenoids (long coils of wire) are particularly useful because the magnetic field from each loop adds to the next, creating a powerful electromagnet.
Quick Tip: Use Fleming's left-hand rule to remember directions - thumb for movement, first finger for magnetic field, second finger for current!
The motor effect happens when a current-carrying wire sits in a magnetic field - it experiences a force that makes it move. This is exactly how electric motors work, and the formula is: Force = magnetic flux density × current × length F=B×I×L.