Electromagnet Principles Student: John Adams

Outline Electromagnets How they are created Magnetic fields Uses

Electromagnets Use electricity to create a magnetic field They can be controlled (turned on and off) Their force or strength of field can be controlled

Electromagnet Basics An electromagnet works on the principle that an electric current not only allows electrons to flow in a circuit, but also generates a small magnetic field. Electromagnetic has a link leading to a youtube video describing Electromagnetics. Electromagnetic Field around a wire

Creating a Stronger Magnet Coils Each loop of coil has a small amount of magnetic pull When the loops are added together the coil begins to act as a magnet with poles

Electromagnetic Field and Strength There are 4 factors that affect electromagnetic strength: Number of turns Current strength Length of coil Types of conductors Now let’s look at each one of those factors

ELECTROMAGNETIC STRENGTH Number of turns The strength of the electromagnet is directly proportional to the number of turn in the coil. By varying the number of turns in its coil can produce very strong magnetic fields and its strength.

ELECTROMAGNETIC STRENGTH 2. Current strength The strength of the electromagnet is directly proportional to the current flowing in the coil. Greater the current flow through the coil, stronger will be the magnetic fields produced.

ELECTROMAGNETIC STRENGTH 3. Length of coil The strength of the electromagnet is directly proportional to the length of the coil. The length of the wire is equal to the length of one loop of wire around the tube. By coiling it up the magnetic force will increase.

ELECTROMAGNETIC STRENGTH 4. Types of conductor Depend on the nature of the core material. The use of soft of core can produces the strongest magnetism

ELECTROMAGNETIC STRENGTH Iron: Iron is a magnetic material. There are magnetic particles inside the iron. In soft iron, these particles will line up with an external magnetic

ELECTROMAGNETIC STRENGTH The soft iron core behaves like a magnet itself. Once the external field is taken away, the core will return to normal. Imagine we put a piece of soft iron in the middle of a coil of copper wire

Example of Modern Electromagnetic Device Loudspeaker You can change the strength of an electromagnet's magnetic field by varying the electrical current that passes through the wires wrapped around it. If you change the direction of the electrical current the polarity of the magnetic field reverses. These effects can be used to move a loudspeaker cone back and forth, creating sound according to the electrical current through the wire. They also can be used to create magnetic fields in a magnetic tape or computer hard drive, such that it stores information.

Summary What three things determine an electromagnet’s strength? Number of turns Current through the coil Length of coil Permeability of core material

References http://www.pkb.edu.my/elearning/Microsoft%20Word%20-%20CHAPTER_4.pdf http://resources.schoolscience.co.uk/CDA/11-14/physics/copch33pg3.html