Magnetism
There is a magnetic field around a magnet. This is a mathematical representation of the interaction between the magnetic material and electrical current. It is represented by magnetic field lines which moves out of the north pole into the south pole.
Diagram of magnetic field lines.
It is very important to note the direction of the arrows on the field lines.
Interaction between two magnets
1. North and South poles attract (opposite pole attract).
Diagram of attractive forces.
2. North and north poles will repel; south and south poles will repel (Like poles repel).
Diagram of repulsive forces for north to north poles.
Diagram of repulsive forces for south to south poles.
Electromagnetism is the study that involves the use of electricity to create magnet and vice versa (that is, using a magnet to generate electricity).
What is a solenoid?
The solenoid is a long coil containing a large number of close turns of insulated copper wire. A magnetic field is produced by the current carrying solenoid. The strength of magnetic field produced by a current carrying solenoid is directly proportional to the number of turns and the strength in the solenoid. It is also dependent on the nature of "core material" used in making the solenoid. When soft iron rods are used as cores, they produce the strongest magnetism. Solenoids are used for making electromagnets.
What is an electromagnet? Diagram
When an electric current flows through a soft iron rod placed inside a solenoid, a temporary magnet is created. It acts as a magnet only so long as the current is flowing in the solenoid. This combination of a solenoid and a soft iron core is called an electromagnet. An electromagnet, therefore, consists of a long coil of insulated copper wire wound on a soft iron core.
Here are some uses of electromagnets:
1. Used in cranes to lift heavy metal.
2. Used in electric bells
3. Used in radio speakers
4. Used in microphones
5. Used in dynamos
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