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ElectromagnetsA 30-foot diameter electromagnetused in research for a superconductorA large electromagnetused to lift scrap metal
ElectromagnetsThe source of electromagnetism is electricity(current) flowing through a coil of wire.
ElectromagnetsA coil of wire can be made into a magnet by passing anelectric current through it.Without electricity,there is nomagnetic forceElectric current applied to a coilcreates a magnetic field
Electromagnetic Strength Increase the number of coils. Increase the electric current flowingthroughthe coil. Add an iron core in the center of the coil.How can an electromagnet be madestronger?
The left hand rule todetermine North PoleNORTH POLE SOUTH POLE
Making a MagnetAn example of a very strong magnet
The magnet is strongenough to lift this 50pound engine cylinderhead.The coil of wire has beenattached to a 12 volt DCpower source making anextremely strong magnet.Making a Magnet
SaturationSaturation KneeY- AxisIncreasingMagneticForceYX- Axis Increasing ElectricCurrentXSaturation of a magnetic field occurs when an increase ofelectric current flow does not increase the strength of themagnetic field as shown by the graph. The knee of thecurve is the point that saturation occurs.
MAGNETIC COIL LOSSES Copper losses - resistance of coppercoils. Hysteresis - magnetic flux inducing acurrent in the core. Eddy currents - magnetic polarity of theiron core is rapidly changed by an ACcurrent causing friction and heatbetween the molecules
MAGNETIC TERMS Flux - Invisible lines of force. Poles - North and South where force isstrongest. Permeability – The ability of a material toconduct lines of force. Residual Magnetism – The ability of amaterial to hold its magnetism for a longtime.
MAGNETIC TERMS Ferromagnetic Material – A material easy tomagnetize. (i.e., Iron Steel, Cobalt, Perm-alloy,and Alnico) Paramagnetic Material- A material that can beslightly magnetized. Diamagnetic Material – A material that is verydifficult to magnetize. Magnetic Laws – Simply stated: Like polesrepel and unlike poles attract.
Review What are the poles of a magnet? Name the magnetic lines of force. List five types of magnets and their twofamilies. List the laws of magnets. Explain two methods for making a magnet.
Review Explain two theories of magnetism. Name five different types of devices that areassociated with electromagnetism? List three magnetic and three nonmagneticmaterials. What will remove magnetic lines of force?