Electric Current and Magnetism In 1819 Hans Christian Oersted a Danish physicist and chemist and a professor placed a compass needle near a wire through which he could make electric current flow ID: 273262
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Slide1
ElectromagnetismSlide2
Electric Current and Magnetism
In 1819, Hans Christian
Oersted
, a Danish physicist and chemist, and a professor, placed a compass needle near a wire through which he could make electric current flow. When the switch was closed, the compass needle moved just as if the wire were a magnet.Slide3
What is an Electromagnet?
Magnets created by electric current flowing in wires.
All magnetism comes from electric current.
The strength of the magnetic field is directly proportional to the amount of current flowing.Slide4
What’s Happening on the Atomic Level?
The electrons moving around the nucleus carry electric charge.
Moving charge makes electric current so the electrons around the nucleus create currents within an atom.
These currents create the magnetic fields that determine the magnetic properties of atomsSlide5
Electric Current and Magnetism
The magnetic field around a
single
wire is too small to be of much use. There are two techniques to make strong magnetic fields from current flowing in wires:
Many wires are bundled together, allowing the same current to create many times the magnetic field of a single wire.
Bundled wires are made into coils which concentrate the magnetic field in their center.Slide6Slide7
What is a Solenoid?
The most common form of electromagnetic device is a coil with many turns called a
solenoid
.A coil takes advantage of these two techniques (bundling wires and making bundled wires into coils) for increasing field strength. Slide8
Strength of Electromagnet (Solenoid)
The magnetic field of a simple electromagnet depends on three factors:
Amount of current in wire
Amount and type of material in electromagnetic coreNumber of turns in the coilSlide9
Right-Hand Rule
The North pole of an electromagnet depends on direction of current.
When the fingers of your right hand curl in the direction of the current, your thumb points toward the North Pole.Slide10
Right-Hand RuleSlide11
Examples of Electromagnets