Carol Cao, Summit View School
electrical arcs, air conductivity, Paschen's Law
Electric and Magnetic Phenomena
- Electric and magnetic phenomena are related and have many practical
applications. As a basis for understanding this concept.
- Students know charged particles are
sources of electric fields and are subject to the forces of the electric
fields from other charges.
- Students know magnetic materials and
electric currents (moving electric charges) are sources of magnetic
fields and are subject to forces arising from the magnetic fields of
- Students know how to determine the
direction of a magnetic field produced by a current flowing in a straight
wire or in a coil.Students know plasmas, the fourth
state of matter, contain ions or free electrons or both and conduct
- * Students know electric and magnetic
fields contain energy and act as vector force fields.
Electrical Source, a Jacob's ladder device. See References to find out how to make one.
Once you have obtained a Jacob's ladder or made one yourself, make sure the wires are enclosed in a tube to help keep air drafts from affecting the results. Apply the power source and watch the arc form.
The Jacob's ladder produces a continuous electrical spark/arc that rises up from the bottom of the device. There is a gap between the two wires extending from the base of the device. The two wires from a narrow "V" shape. When voltage is given to the gap, a spark forms at the bottom of the wires where the gap is narrowest. This spark quickly changes to an electrical arc. The arc takes in much of the electrical supply and the voltage across the gap is reduced. As air heats up around the arc, the air rises carrying the electrical current up the ladder. As the arc moves up, the distance between the two wires increases. The arc becomes more and more unstable and will eventually break. The voltage across the bottom of the device and electrode begins to rise again forming another spark.
- Inculde at least three questons (with answers) that you can ask to assess understanding of the principles ilustrated
Everyday examples of the principles illustrated
spark plugs, electrostatic machines, x-ray machines, microwave oven transformers,