ac vs. dc current electromagnetic fields dc direct current current that is produced in a circuit by...
TRANSCRIPT
AC vs. DC CurrentElectromagnetic Fields
DC Direct Current
Current that is produced in a circuit by a steady voltage source. Direct current is when electrons flow in one direction in a circuit only.
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In direct current the voltage will go to maximum or PEAK (almost) instantly so on a graph it looks like this.
Vol
ts
Time0
Electrons flow from – to +
1 sec
AC Alternating Current• Current that is produced by a voltage source
that changes polarity, or alternates, with time.
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In alternating current the voltage goes to PEAK positively then reverses to zero, the current then goes to PEAK in the negative.
Vol
ts
Time
0
When the electrons have gone once in each direction makes cycle and is represented with a sine wave as seen in the graph.
When armature cuts magnet field at peakWhen armature runs parallel to field at zero
http://www.walter-fendt.de/ph14e/generator_e.htmLink needs Java to run
Draw this graph on your paperDraw this graph on your paper
Electromagnetic Fields• When current flows through a
conductor a magnetic field is produced about the conductor.
• The magnetic field does not have a north or south pole but it does have direction which is determined by the direction of the current.
• A compass will deflect when in the area of these electrically induced magnetic field
Wire in a coil• Take the same wire as in the
previous slide and put the wire into a coil and now the magnetic field will have a north and south pole.
• Add an iron core and this increases the magnetic field, also called a solenoid
Solenoid Applications
• Door Bell-
Click on each picture to go to a supporting youtube video
• Relay Switch-
• Speaker-
http://youtu.be/KqcT-oYImFQ
Motor Action
• When a current is applied to wire that is in a magnet field the field created by the electron flow causes a force that will repel the wire causing it to move. This is called motor action.
Electric Motors
• An electric motor uses the principle of the repelling force to turn electrical energy into mechanical energy.
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