R.Lawrence( )1 Electrical/Electronics Volume 2 of 5 Grade 11 Magnetism & Electromagnetism

R.Lawrence( )2 What is Magnetism? Magnetism is the force of attraction or repulsion in a material. Certain materials such as iron, steel, nickel, or magnetite exhibit this force while most other materials do not.

R.Lawrence( )3 What are Magnets? A magnet is a material or object that produces a magnetic field. This magnetic field is invisible but is responsible for the most notable property of a magnet: a force that pulls on other ferromagnetic materials and attracts or repels other magnets.

R.Lawrence( )4 Magnetic Field A magnetic field can be represented by lines of induction or flux lines. These lines are invisible and are produced by magnetized material or by electrical currents. Magnetic fields are electrical in nature, and the magnetic field caused by a long straight line of current is simulated in Figure 1.

R.Lawrence( )5 Magnetic Fields Fig.1

R.Lawrence( )6 Magnetic Materials Ferromagnetic - metals that are easily magnetized; iron, nickel, cobalt, manganese Paramagnetic - metals that can be magnetized but not as easily as ferromagnetic; platinum, titanium, and chromium Diamagnetic - metal or non-metallic materials that cannot be magnetized; copper, brass, and antimony

R.Lawrence( )7 Electromagnetism This is the changing magnetic field produces an electric field (this is the phenomenon of electromagnetic induction, the basis of operation for electrical generators, induction motors, and transformers). Similarly, a changing electric field generates a magnetic field

R.Lawrence( )8 Electromagnetism Creation

R.Lawrence( )9 Gauss's Law for magnetism It states that the magnetic field B has divergence equal to zero, in other words, that it is a solenoid vector field. It is equivalent to the statement that magnetic monopoles do not exist. Rather than "magnetic charges", the basic entity for magnetism is the magnetic dipole. (Of course, if monopoles were ever found, the law would have to be modified, as elaborated below.)

R.Lawrence( )10 Coulomb's Law of Magnetism The magnitude of the electrostatic force between two point electric charges is directly proportional to the product of the magnitudes of each of the charges and inversely proportional to the square of the total distance between the two charges.

R.Lawrence( )11 Reference For further reading you can check out the following websites:

R.Lawrence( )12 Take Quiz Now