![]() Study the voltage directly by simply connecting a probe to one of the channels on an oscilloscope and you can probe the changing voltage spatially. ![]() The circuit is providing a high-frequency alternating voltage which is necessary to "step up" the voltage to the levels needed to operate the plasma globe. You will also notice no directional dependence of the diode because the field is oscillating rapidly. This demonstrates that the voltages are decreasing with radial distance or (equivalently) that the Electric Field is radial. Bring either of these near the plasma ball and they will light up when aligned radially, but not circumferentially. This Electric Field can easily be investigated with a small neon bulb or light emitting diode (LED). The Electric Field created by the Tesla coil reaches beyond the glass dome and into the air surrounding the plasma ball. Investigate the oscillating electric field Once again, be cautious because the glass will heat up.Ĥ. With practice, you should be able to get just a single vertical thread. ![]() However, a vertical streamer at the top will be stabilized by the buoyancy. For this reason, it is difficult to get a horizontal streamer to remain unbroken for more than a second – not unlike a Jacob's Ladder. The plasma threads are very hot and they will rise due to their buoyancy in the other gases inside the plasma ball. Fingernails conduct electricity better than the skin and underneath it is a tissue that is dense lined with pain nerves. You should avoid touching the spark with your fingernail. If you are too shy to touch the spark with your hand, you can touch a metal key (or any conductor) to the coin and the spark will still form while providing additional insulation. You can also have fun burning small pieces of paper with the spark. Let the students touch lightning too and use this sparking technique to explain how lightning forms due to the Electric Field ionizing the air. The tip of the finger will now show a few harmless burn marks that will rub off in a day. This spark will not cause pain, or electric shock, but will be hot and if you hold your finger their long enough it might begin to hurt. By bringing your finger only a few millimeters above the penny, you will be able to elicit a spark from the top of the coin. The very high voltages of the plasma ball can easily polarize a coin (or piece of aluminum foil) placed on top of the plasma ball. It is important to remember that plasma is very hot and it will slowly conduct heat through the glass. This is more obvious when you bring a finger to the plasma ball. Plasma is also an excellent conductor so, once one filament forms, it becomes generally stable allowing for more current to flow through it (similar to a lightning strike). A plasma ball operates on a high-frequency alternating voltage, and for this reason, the charges do not have much time to move in demonstrably measurable distances and get deflected. In order to witness deflections of plasma, he charges must move for long enough times. Moving plasmas can usually be controlled by magnetic fields, but this will not be visible on the plasma of a plasma ball. Like a gas, plasma has no fixed volume and like other fluids it does not have a fixed shape. When the freed electrons are regained by ionized atoms the bonding energy is often released as visible light therefore glowing is a signature of most plasma. This means that newly created plasma has undergone ionization (the phase transition that is after melting and boiling). ![]() Plasma is a gas-like collection of atoms that have a large number of free electric charges. Most physical science classes require that students have a cursory understanding of plasma as the "fourth state of matter." This title is misleading because plasma is the most common state of matter in the universe and plasma was in fact the first state to exist after the big bang. As you approach the plasma ball you become polarized by the electric field and this attracts more charge to you. This is due to the polarization of your body (a decent conductor). On first inspection, you will notice that the plasma ball responds to your touch. This process is known as cascade/avalanche or impact ionization. The Field is strong enough to ionize the gases in the ball (it pulls their electrons off) and the freed electrons undergo collisions which liberate more electrons from other gas molecules. A very large voltage is created by a Tesla coil-like circuit and this creates a high electric field between the central electrode and the inner glass. The plasma ball is an engaging and safe tool for studying high voltages and the electric field and can be used in middle school, high school, and college level physics courses.
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