Factors that affect the Magnetic field of an Electromagnet 1. The core material The denser the material the stronger the field 2. The current intensity Higher the current stronger the magnetic field 3. Number of loops (number of turns) More turns gives a stronger field.

Cores  A Core is the object that is inserted into the solenoid, creating an electromagnet.  Different metals can be used for the core: iron, steel, nickel or cobalt.  Iron is most commonly used because when you turn off the electricity it demagnetizes.  Metals like steel remain magnetized thus creating a permanent magnet. Do not want a permanent magnet for the core

Core Material  Ferromagnetic cores strengthen the magnetic field Iron, steel, nickel & cobalt Iron is a VERY GOOD core  Wood, plastic and Aluminum are not very good products for a core

Number of Loops  As the number of loops increases, the strength increases Few loops Many loops

Current Intensity  As the current intensity increases, the strength increases I = 5 ampsI = 10 amps

Which has a stronger magnetic field? ABAB Iron Wood 1 - Number of loops is the same 2 – Intensity is the same 3 – But the core is different I = 5 amps Result: (A) Iron is better because it is a ferromagnetic core

Which has a Stronger Magnetic Field A B Iron Iron  # of loops are different  Intensity is the same  Core is the same I = 2 amps 3 loops5 loops Result: B is stronger: more magnetic loops = a stronger magnetic field

Which has a Stronger Magnetic Field A B Iron Iron  # of loops is the same  Intensity is different  Core is the same I = 2 ampsI = 10 amps 5 loops Result: B is stronger because current intensity is greater

Which has a Stronger Magnetic Field A B Nickel Nickel Whenever the loops & the current intensity are different but the cores are the same, use the following equation I = 5 amps I = 2 amps 3 loops5 loops Strength of field = current intensity x (# of turns) A 15 = 5 amps x 3 turns B 10 = 2 amps x 5 turns A therefore has a stronger magnetic field

Mathematical Relationship  To find the strength of the electromagnet scientists use the following equation: F = IN F is force or strength of the electromagnet I is the current intensity traveling through the wire N is the number of loops around the core Remember

Which Electromagnet has the Strongest Magnetic Field Current = 10A Turns = 6 Current = 7A Turns = = 10A x 6 turns70 = 7A x 10 turns Strongest

Factors affecting magnetic field:  Core material,  Iron is always the best core material  Number of turns  The more loops the stronger the field  Current Intensity  High current results in stronger intensity

Origins of Magnetism of Matter  Scientists believe that magnetism comes from spinning electrons around the nucleus of the atom.  When atoms clump together they form a domain.

 Similar electron spins produce a strong domain, where as opposite electron spins cancel one another out and produce a weak domain.  If enough domains align in the same direction, this will create a magnetic field. Origins of Magnetism of Matter

How to Magnetize an Object  Bring the ferromagnetic substance in contact with another magnet.  Bang the ferromagnetic substance (example: striking a nail repeatedly).  Heat up the substance and cause the domains to align.  Run electric current through the ferromagnetic substance.  Please note that all of these methods can also de-magnetize a magnet.