Tesla Coil Instructions and Applications

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Science First® would like to thank Robert Lichtenberg of Sugar City, Idaho for invalu- able technical assistance with these instructions.

Warranty/Replacement Parts: Ball Terminal We replace all defective parts free of charge. Additional replacement Corona Cap parts may be ordered by referring to part numbers above. We accept Long Master Card, Visa, American Express Wire and purcahse orders from educational institutions in good standing. All products warranted to be free from Secondary defect for 90 days. Does not apply to accident, misuse or normal wear and Primary tear. Terminal Post Introduction: The Tesla Coil is an air-core Primary Capacitor transformer with primary and sec- Spark Gap ondary coils tuned to resonate. The primary and secondary function as a step-up transformer which converts Vibrator relatively low-voltage high current Knob to high-voltage low current at high Cord frequencies. Diagram 1 The Tesla Coil demonstrates the fundamental principles of high frequency electrical phenomena. It The capacitors are two large cyl- and closes when the magnetic field shows the principles of ionization of inders on either side of the spark gap. decays. This occurs 120 times per gases and behavior of insulators and They are high voltage capacitors of a second - each time the AC current conductors when in contact with high predetermined size and value. changes polarity of the electromag- frequency electrical fields. The primary coil is a pair of thick net. Its inventor, Nikola Tesla, con- insulated copper wires located next The capacitors charge up when ceived it to be a means to transmit to, but not touching, the second- the buzzer contacts are open, since electrical power without wires. An ary and connected in series with the the current passes into them to com- antenna would pull the transmitted capacitors and spark gap. plete the electrical circuit. When the electrical energy into the electrical The secondary is a cone-shaped contacts are closed, the capacitors system. You can also consider it a coil (cone-shaped to keep the coil are shorted together and current does simple radio transmitter. Operating compact and for manufacturing rea- not pass into them. The open contacts within a broad range of high fre sons as less wire is needed) consisting allow the air in the spark gap -the quencies, which transmits power of 400 turns of thin enameled copper small space between open contacts rather than information. wire. It functions as a transformer to ionize, which permits a discharge by stepping up voltage to high levels. that short circuits the transformer and Components: The high voltage is given off by the capacitors. But the capacitors retain The Tesla Coil consists of a vibra- terminal. their electric charge, since the func- tor or transformer, two high voltage tion of a capacitor is to store an elec- capacitors, a primary, and a second- trical charge and thus provide energy’ ary connected to a ball terminal or How a Tesla Coil Works: to create an electromagnetic field. antenna. Refer to Diagram 2. When the This spark taking place in this The vibrator is composed of an plug is inserted into 110 AC current spark gap does not consist simply of air slot core around which coils of (220 volt for #10-206), electricity a single spark passing in one direc- copper are wound; and a buzzer flows through the vibrator, an iron tion, as would appear to the eye, but which consists of two tungsten points core with hollow center wound a number of separate sparks passing or contacts which open and close by with coils of copper wire. This core back and forth in opposite directions. means of a spring as alternating cur- becomes an electromagnet. The buzz They take place so rapidly you cannot rent and electricity passes through the er, 2 tungsten contacts opposite each see the direction change. The time core and discharges in the spark gap. other, not quite touching, pulls apart during which the spark appears to when the electromagnet is activated

“ring” at the chosen high frequency . Primary Resonance: 1 µ H at .025 µ F Ball Termi- Resonance may also be compared nal 1 Primary, L = 1 µ H 2 π LC to a swing. When inductive imped- or 1 x 10-6 H F = 1.07 MHz ance and capacitive impedance of a circuit are equal, the electricity .05 µF 1600 E oscillates back and forth between inductive component (primary) and Buzzer Spark Gap capacitive component (capacitors, 2 Spring also called condensers). When push- Secondary, 90 pF at ing a swing, a person can cause large Capacitors, Total 50,000 E forward and backward motions with .025 f at 3000 E µ Iron Core Grounded Plug small pushes administered at the correct frequency. Applying energy at correct frequencies builds up high µ L2 = 277.77 H potentials in a resonant circuit. G =90 pF A person in a swing weighing 200 AC Choke Drive pounds may be pushed by a small Diagram 2 Tesla Coil 1/4 Wave child about 50 pounds who may push with only one pound of force. If he pass may only be a fraction of a sec- from the 60 cycle component of the times his pushes to coincide with ond, but during that time the current current, the electrical circuit will not the direction of the swing and keeps may have oscillated back and forth be complete in regard to the 60 cycle adding a pound of force each time, he several thousand times. component and you will not receive will eventually have to stop to avoid The electromagnetic field is a shock if you touch the coil directly . hurling the person in the swing out formed by the primary which Another safety feature is the fact that into space. converts the charge stored in the an air-core transformer by its nature An analogy used by inventor capacitors to magnetic energy. The does not pass 60 cycle current well. Nikola Tesla himself is to picture a electrical charge is transferred to the wine glass broken by a violinist’s primary by the capacitors when the note. The glass is shattered because magnetic field in the iron core decays. The result is that high frequency the vibrations happen to be the same When the magnetic field in the iron electrical energy is built up by the frequency as the vibrations of the core is reactivated, the field generated generation and decay of the magnetic glass. in the primary is the one to decay, field in the primary every halfcycle, Since at the right resonant and the electrical charge is transferred often reaching many million cycles frequen cy, the AC resistance, or back to the capacitors with every per second. reactive impedance, is zero with the half cycle, a charge of increasingly When the high frequency is great right coil and capacitor, and now the higher voltage as each activation of enough and reaches the voltage maximum current can flow according the magnetic field adds to the charges predetermined by the size and value to formula: 1 previously generated. of the capacitor , the primary induc π The vibrator also acts as an air es a magnetic field in the secondary. 1/2 LC = Fr core transformer, boosting the voltage Inducing means a moving magnetic The secondary, like the vibrator, to medium high levels with every field causes a magnetic field to form functions independently as a step- half-cycle pulse of AC current. The in another wire coil located close to, up transformer of about 3,000 volts. high frequencies produced are rich or inside, the first coil. Since it has many more coil turns of in harmonics since each pulse of The primary consists of two thick copper wire in its secondary from electricity across the spark gap is insulated copper wires which are the primary voltage of 110 volts of composed of many surges of electri- resonated by the capacitors to equal AC input, then electrical energy is cal energy. the natural resonant frequency of supplied. The capacitors in this Coil have a the secondary. When the resonance As the electrical energy from the particular size and value. They serve equals that of the secondary, a mag- vibrator is fed to the capacitors of the the dual function of storing electric netic field is formed in the secondary. primary air core transformer and coil charge and filtering through the high Resonance may be compared to a at its base, it now creates another in- frequency component of electrical cymbal: when a cymbal of a certain dependent circuit of the vibrator type current while blocking low frequency size and weight is struck, it rings at a transformer. The vibrator secondary 60 cycle current. This is a safety specific frequency. In the Tesla Coil, output of 3,000 v is applied to this feature, since by isolating the primary the right capacitors and secondary primary circuit, known as the air core

How To Operate: stranded wire. This is included in tesla resonant transformer (oscilla- Use Tesla Coil on bench or table your accessory kit. Cut into 1 ft. tor). with nonmetallic surface to rule out and 3 ft. lengths. Its energy is then induced to the danger of electric shock. Plug into Uninsulated copper wire. Also cone shaped coil with the ball on top. grounded outlet supplying 110 volt included. Cut wire into lengths It is the number of turns known as 60 cycle current (in case of 10-206 required in the following experi- inductance and its self-capacitance. Tesla Coil, 220 volt electricity). Volt- ments. When the primary supply is properly age of household current may vary Adjusting for Peak tuned to the secondary, a high volt- slightly. Turn black knob on vibrator age, high frequency output is devel- Performance: until a buzzing sound is heard. For best results, adjust your Coil for oped of about 50,000 volts. proper operation. Q. How do capacitors filter through the high In this case, this unit’s total 1. While machine is unplugged, primary capacitance is .025 microfar- frequency component of the electrical current while blocking the low frequency 60 fasten wire to ball terminal. ads at 3,000 volts and its secondary cycle current? Take small piece of thin bare capacitance is 90 picofarads at 50,000 A: Capacitors pass AC much better than DC. wire provided and fasten under- Capacitors are arranged as a high-pass volts. It is the square root of the neath ball terminal by winding it primary to the secondary capacitance filter placed in series with the primary. At 60 Hz, this is nearly an open circuit. At 1 around the screw tip to which ball that determines the approximate out- megahertz, though, the capacitor puts very terminal is attached. Point free end put voltage of 50,000 volts, according little reactance into the circuit. upward. to the following formula: 1 2. Plug in Coil. Plug into ordinary π Xc = 2 fc where X is capacitive reactance, f is fre- 110 volt household outlet (for µ -6 c Cp or .025 F or 25 x 10 10-206, 220 volt). Light stream- Cs 90 pF 90 x 10-12 quency, c is capacitance. So as frequency increases, X gets smaller. ers will issue from the tip of the c wire, since the wire’s sharp end = Total 277.77 will break down the surrounding = 16.66 x 3000 volt vibrator second- Adjust with Discharge Wand: air more easily than will the ball ary terminal. With the current at maximum The discharge electrode is a large hooked metal rod. Its uncurved end 3. Adjust buzzer knob until longest resonance, a high voltage, high possible streamers emanate from frequency of one million impulses are is placed in the hole in the top of the primary terminal post - a black wire end. Long streamers indicate produced at the ball of the secondary. circuit of primary and second- The Tesla transformer does not knob protruding from the plastic base. When you plug in your Coil, ary coils are resonated. In this function on turn ratio windings. It condition your machine operates functions instead on the ratio of the discharges will pass between the ball terminal and the tip of the discharge at maximum efficiency. primary capacitance to the secondary 4. It may be necessary to readjust the capacitance. electrode. Long, intense discharges mean maximum output. buzzer knob during operation as The secondary, like the vibrator, the unit warms up. This is normal. functions as a transformer. Since it The discharges can be seen from has more coils of wire than the prima- a distance, making this a good class ry, it boosts the high voltage. demonstration. How To Handle High The secondary is a cone-shaped Additional Materials Needed: Some experiments that follow require one Frequency High Voltage coil located next to but not inside or more additional materials. the primary . Only the first few turns Electricity Safely: One 100-200 watt clear glass incan The electricity generated by the are within the electromagnetic field descent light bulb, nitrogen Tesla Coil does not pass through your created by the primary . Only a small filled. Standard 100-200 watt light body. It flows harmless over your difference in voltage exists between bulb. The higher the wattage, the skin. each turn of the coil and the one more visible the results. A frosted High-frequency currents possess preceding it. This low voltage differ- bulb will work with less visible unusual properties. Since they travel ential per turn prevents voltage from results. only on the surface of wires and con- breaking down copper wire insulation Fluorescent lamp tube. Any size, 40 ductors, a hollow tube conducts this and short circuiting the secondary. watt standard recommended. type of current as well as a solid rod The secondary produces a current One 2 to 3 volt miniature screw- of the same diameter. High frequency called high frequency electricity. base flashlight bulb currents do not cause a shock. You High frequency currents reverse their Miniature screw-base lamp socket can take a piece of metal, approach a flow, or alternate, from 100,000 to Aluminum foil high frequency coil and throw a spark one million times a second. 4 foot length of 20 gauge, plastic 2 to 3 feet long without any sensation

except slight warmth. Experiment 2: Experiment 3: However, while high frequency How a Conductor Affects the How Insulators Behave at high voltage electricity will not Flow of High Frequency High High Frequency produce a shock, it can cause a burn You Need: at one small point of contact. This is Voltage Currents • 100-200 watt clear glass light bulb because the output is concentrated in You Need: • Short length of bare wire • Special lamp socket, included a small area (the vicinity of the ball • Piece of metal terminal) forming an electrical arc • Other insulators (wood, plastic) that becomes intensely hot. With the ball terminal in place, plug in your Coil. Examine ball ter- This concentration of current may With the Coil unplugged, the re- minal to see if there are any signs of be broken down by discharging the move ball terminal from top of Coil. an electrical discharge issuing from it. coil with a small piece of metal held Screw the special lamp socket on The ball terminal, being metal, close to the ball terminal. We suggest exposed threaded stud. is a conductor. However, there will a coin, knife or piece of bare wire. Mount the light bulb onto lamp normally be no such discharges, since As you approach holding this item, socket by screwing it on. the smooth rounded surface of the you increase the area of contact and Plug in the Coil, place your finger ball causes a uniform stress on the reduce the current per unit of area, tip on top of the glass light bulb and surrounding air. which will not cause a burn. move it quickly over surface of bulb. Operate the Coil in a darkened You can also move your finger Observe the discharges which room. quickly so that it does not remain in take place in the bulb and lightning- Examine the ball terminal. (If the the same position with relation to the like feelers that reach out from the Coil is adjusted properly it may break ball terminal. This results in a safe bulb’s electrodes to a point on the down the surrounding air despite flow of high frequency high voltage inner surface of the bulb directly the smooth, round shape of the ball electricity over your skin. beneath your finger. terminal. Any such discharge will be Low frequency currents, either Take piece of metal and touch most noticeable in the dark.) AC or DC. do not possess this ability. bulb with it. Observe difference in Unplug the Coil and unscrew the They pass through the body directly appearance of discharges. ball terminal from its top. (specifically through the liquid-filled Although the high frequency cur Take a short length of thin, bare tissues). A voltage that can produce rents from the Tesla Coil pass through wire, preferably pointed at one end. serious injury in the form of low fre- the glass of the light bulb and into Fasten wire to the screw end from quency AC or DC will flow over the your finger tip, you receive no physi- which the ball terminal has been surface of your skin if it is in the form cal sensation. The reasons are: one, removed, with pointed end of wire of high frequency electricity. high frequency currents flow over the bent upward. The longest possible light stream- surface of the skin; two, the total cur- Plug in Coil and note profuse ers indicate the circuit of the primary rent is distributed over the entire area discharge that issues from the sharp and secondary coils are resonated. In of your finger tip which is in direct bare point. This type of discharge is this resonated condition your machine contact with the glass. known as Corona Discharge. operates at maximum efficiency. Remember to keep your finger This experiment illustrates the moving quickly. You may get a burn fact that high frequency high voltage if you concentrate the discharge at a electricity issues more readily from Experiments single point on your finger. a conductor with sharp points than This experiment shows that glass, a conductor with smooth round sur- an excellent insulator for medium Experiment 1: faces. (This is the reason that sharp and low frequency currents, is readily bends, pointed projections and sharp Discharging broken down by high frequency high You Need: corners are avoided in wiring high voltage electricity. Test the insulating • Piece of metal (coin, key, bare frequency equipment.) properties of other materials. uninsulated wire etc.) A practical example of this prin- Remove the light bulb and special ciple is the way high voltage metal lamp socket and return ball terminal enclosures of televisions are wired. Hold a small piece of metal in to the top of the Coil. one hand. Plug in Tesla Coil and ap- Hold wood, plastic or paper in proach ball terminal with metal. The direct contact with the ball terminal high frequency high voltage electrical with one hand while trying to draw discharge forms an arc between ball a discharge through the insulating terminal and a metal object. See how material to a piece of metal in your far out you can draw an arc. other hand.

Experiment 4: Experiment 5: dard high wattage light bulb (contain- Ionizing Gases by Electrical How Pressure Affects ing nitrogen gas), a fluorescent tube Stress Ionization of Gases (containing a combination of mercury You Need: You Need: vapor and argon), and a neon lamp • Fluorescent lamp tube, 40 watt • 100-200 watt clear glass light bulb (containing neon). • Neon lamp. Included Hold each bulb by the glass itself, • Short length of bare wire Operate your Coil with the ball not touching the metal base. Bring terminal in place. Hold bulb by its each bulb in turn toward the ball glass, not touching metallic base). terminal while the Coil is operating. While the Tesla Coil is not in Bring the base of the bulb slowly Stop when the gas in each bulb ion- operation, attach the neon lamp to the toward the ball terminal. Stop at the izes. ball terminal. The neon lamp is a very point where the gas in the bulb begins Compare the distances from the small light bulb (N E ) with two thin 2 to ionize. ball at which the three gases ionize. copper wires protruding. Observe the distance between The standard high-wattage light Use one of the thin wires to attach the ball terminal and the point at bulb must be brought much closer lamp to ball terminal. Wind the wire which the bulb begins to glow. The to the ball terminal before its gas around screw stud onto which the ball gas contained in the bulb ionizes at ionizes. Therefore nitrogen must terminal is mounted. the same distance from the Coil even be brought into an area of greater Plug in the Coil and watch how though the electrical stress at this electrical stress than either neon or brightly the neon lamp lights up point is much less than it is at the ball a combination of argon and mercury despite the fact that it is connected to terminal’s surface. vapor before it breaks down. the Tesla Coil by only one wire. Observe that although the gas With the short length of bare wire inside is ionized, the gases in the (NOT your hand) touch the glass bulb surrounding air are not. In fact, the Experiment 7: of the neon tube. Watch how the gases in the atmosphere do not ionize Sparking Potential red-orange discharge becomes even even when they are in contact with You Need. brighter and more concentrated. Not the ball terminal, where the electro- • About 7 inches of stiff bare wire only do the electrodes in the neon static stress is greatest. (included - cut to desired size) lamp glow - the entire bulb exhibits a The gas usually used in high red-orange glow. wattage incandescent light bulbs is While the Coil is unplugged, con Unplug the Tesla Coil. Remove nitrogen, a small amount of which is nect one end of length of stiff bare neon lamp from ball terminal. Plug introduced into what is otherwise a copper wire to the primary terminal in the Tesla Coil and approach ball vacuum inside the bulb to prevent the post, a plastic knob protruding from terminal holding fluorescent light filament from growing brittle. The the base. bulb in your hand. nitrogen is therefore at very low pres- Connect the wire to the termi- Note the difference in color of the sure inside the bulb. nal post by bendine one end of the fluorescent light bulb compared to the This experiment shows that a gas wire into a U shape. Place this bend neon lamp. at low or reduced pressure, such as into the banana jack on the base of The glow appearing in both lamps the nitrogen in the evacuated light the unit. Make sure the wire is held is caused by ionization. Ionization bulb, will ionize more easily than the securely in position, with its free end occurs when 2 atoms collide, splitting same gas at atmospheric pressure. projecting up into the air. Operate off one or more electrons and giving Tesla Coil and move free end of wire off energy in the form of light. Every toward terminal by hand. Stop at gas will produce its own characteris- Experiment 6: How Gases Differ in the Ease point where a spark jumps between tic color when it becomes ionized. free end of wire and terminal. When the gases in the neon and With Which They Ionize The distance between the free end You Need. fluorescent tubes are subjected to of wire and the ball terminal rep- • One fluorescent tube, any size high electrical stress at low pressure. resents the distance over which the • One 100-200 watt clear glass light Their atoms are excited and give off electrical stress generated by the Coil bulb characteristic glows. In the neon tube, breaks down, or ionizes, the air. The • Neon lamp (included) neon gas is excited; in the fluorescent amount of electrical stress needed to tube, mercury vapor and argon gas. create a spark is called the SPARK- Certain rare gases, such as neon, ING POTENTIAL. For normal dry argon, xenon, krypton and helium, air, the sparking potential is 30,000 v will ionize more readily than others per cm. due to their atomic structure. This is demonstrated using a stan

By measuring the distance between Experiment 9: Experiment 10 the free end of wire and the surface High Frequency High Voltage Transmitting High Frequency of the terminal, and by assuming Electricity Electricity Over A Single that the sparking potential between You Need: Conductor the two is 30,000 volts per centime- • One 100-200 watt clear light bulb ter, you can estimate the sparking You Need: • 12 inch length of plastic stranded • Special lamp socket (included) potential that exists between the wire (included) wire and terminal. • One 100-200 watt clear glass bulb • Special lamp socket (included) • One 3 foot length of plastic 20 gauge stranded wire (- cut to size) Experiment 8: • One 8/32 screw Operate the Tesla Coil and adjust How High Voltage Power is • Glass or plastic tumbler Transmitted for maximum output as follows: turn buzzer knob counterclockwise (fac- You Need: Cut 3-foot length off 4-foot ing Coil with buzzer on your right) • 2 lengths of bare copper wire, plastic stranded wire. Strip insulation until buzzer just stops working. Slow- about 12" and 7" in length (in- off both ends to a length of about 1/2 ly turn buzzer knob clockwise and cluded. Cut to length) inches. observe changes occurring in light With ball terminal in place, fasten bulb. (The Tesla Coil is accurately Fasten 12" length of bare copper one end of wire to screw stud onto adjusted as it leaves the factory. You wire to ball terminal of the Coil by which terminal is mounted. Connect will be able to determine the point at winding it around screw stud onto other end of wire to base of lamp which it just begins operation by first which the ball terminal is secured. socket. Do this by winding wire turning the knob counterclockwise.) Fasten 7" length of bare copper around threaded spacer at base of The discharges taking place wire to the primary post as before. socket and fastening on screw to hold inside the light bulb have differing Position two wires in a vertical wire in place. characteristics. At one setting, they direction, parallel to each other and Stretch wire out to full length be resemble slow-rising, smoke-like 1- 1/ 2 inches apart. This simulates a tween light bulb and Coil so it has no streamers. At another setting, they high voltage power transmission line, contact with other objects. take the form of miniature bluish- in which two wires are spaced widely. Install high-wattage tight bulb in colored lightning bolts. Operate the Coil and observe the lamp socket. Insert bulb inside glass. At a third setting, you observe ionization that occurs. (This is best if The reason for this is that the light quick, erratically moving little points performed in a dark room.) bulb must be insulated from table or of bluish flame travelling up and Note how ionization is confined to bench on which Coil is placed. down the wires inside the lamp a zone surrounding the two lengths of Operate Tesla Coil. Observe how Brush discharges produced by wire, and how it takes the form of a high frequency electricity is car- high frequency electricity are more visible corona discharge. ried by single wire (with no second pronounced in a gas at reduced pres- Gradually decrease the distance wire to serve as return path) to light sure (as in low-pressure nitrogen between the two wires until the point bulb. Once reaching bulb, the high inside light bulb) than in air. is reached where the air breaks down frequency high voltage electrical Remove the special lamp socket or sparks. Observe the effect that currents stream out from its filaments from top of the Coil. Strip insula- decreasing the spacing of the wires to ionize gas inside bulb. From there tion off both ends of 12-inch piece has on the corona discharge. they pass into the surrounding air and of plastic stranded wire to a length High voltage transmission lines eventually back to the Coil of about one inch. Fasten one end of work in a similar way. Two lines This experiment illustrates how wire to screw stud from which lamp far apart run parallel to each other. air is used as the return path between socket has been removed, with other When the air surrounding the wires light bulb and the Tesla Coil where end protruding upward in vertical of a high voltage transmission line no second wire exists to serve as direction. Fan out individual strands becomes ionized, the ionization is return path. confined to a zone around both wires of free end of stranded wire so they and produces a discharge in the air are arranged like a comb. called a corona. Operate the Coil at different set The distance between the two wires is tings of buzzer contacts (as above). crucial: it must be far enough so that Observe the types of brush discharges sparking between does not occur. that result. Replace the ball terminal with a special socket. Insert a 100-200 watt clear glass bulb into the lamp socket.

Experiment 11: 2 to 3 volt screw-base flashlight lamp Experiment 13: Demonstrating the Two into the socket fastened to top of the How an Insulated Conductor Components of High- Coil. Operate the Coil. Affects an Electrostatic Field The flashlight lamp is short- Frequency Electrical Fields You Need: circuited by this wire loop. No • One Neon lamp (included). You Need: electrical energy can come from the • 12" stranded wire (included) • Small radiating plate tied with electrostatic radiating field.The field piece of string or rubber band • One 2 -3 v screw-base flashlight is weak, which can maintain but not bulb initiate ionization. And yet the flash- Tie a piece of string through the • One fluorescent tube, any size light lamp glows brightly. The energy • Radiating plate, any (included) hole at one end of the small plate or for this must come from the electro- loop a long rubber band. (This insu- magnetic induction field generated by lates the radiating plate from direct Unplug the Coil and remove the the Tesla Coil. ball terminal. Fasten radiating an- contact with your hand.) tenna plate to screw stud by placing With ball terminal in place, oper small hole in bent “L” of plate over ate the Coil. Hold the neon lamp by its bulb and bring toward the ball stud. The bulk of plate will project Experiment 12: upward vertically. Secure plate by terminal. Stop at the point at which screwing ball terminal back onto How Faraday Shields Affect the neon gas in the lamp ionizes. screw stud. Electrostatic Radiation Withdraw the lamp to a position Plug in the Coil. Hold base of You Need: just beyond that in which neon gas fluorescent tube and approach radiat- • 12" square piece of metal foil deionizes or ceases to glow. ing antenna plate. When you reach • Neon lamp (included) While continuing to hold the point where gas in tube ionizes, • Make a simple Faraday Shield by lamp in this position, pick up the slowly move tube away. Observe how cutting slots in the metal foil to string or rubber band attached to the gas in tube, once ionized, remains resemble comblike teeth. ( Diag. small plate with your other hand. ionized even when the tube is moved 3) Bring the suspended plate toward away to point where the electrostatic A Faraday Shield is a network of the neon lamp until it touches one of stress is much lower than required to parallel wires connected to a common lamp terminals (one of the thin wires produce ionization in the first place. conductor at one end, like a comb. protruding from the base). The two components of high The common conductor is grounded. Observe how neon lamp ionizes frequency electrical fields are: an It provides electrostatic shielding for when insulated conductor (the plate) electrostatic radiation field and an the electromagnetic component. touches one terminal. electromagnetic induction field. With the ball terminal in place, Break contact with the conductor This experiment demonstrates the operate the Coil. Hold neon lamp by removing the plate. Observe that effect of the electrostatic radiation by glass bulb and bring toward ball lamp stops glowing. field. Its electrostatic stress is insuf- terminal until neon gas ionizes. Stop This experiment shows the effect ficient to initiate ionization (shown at this point. With the Faraday Shield of an insulated electrical conductor by bringing the tube close to the Coil in your other hand, lower it slowly on an electrostatic field. Introduc- to cause it to glow) but is sufficient between terminal and lamp. (Holding ing an insulated conductor alters to maintain ionization in a gas at the shield provides the ground needed the electrostatic stress distribution reduced pressure (shown when you for high frequency currents.) by concentrating stress around the moved the tube away). The radiation conductor. The conductor will then field can ionize a gas but cannot light ionize lamp when lamp is located at greater distance from ball terminal the filament in a lamp. Diagram 3 Remove antenna plate. Take 12" than distance required to ionize lamp length of wire, strip 1/2" insulation in the first place. from both ends, and form a single- turn loop 3 -3 -1/2 inches in diam- Experiment 14: Observe how the neon lamp eter. When Coil is unplugged, arrange Stress Distribution on deionizes or stops glowing when loop around corona cap near top, Faraday Shield is between lamp and Insulated Conductor in beneath ball terminal. Coil. Bring neon lamp closer to ball Electrostatic Field Fasten ends of plastic wire terminal and repeat procedure. This You Need: (scraped free of insulation) to each shows how a simple Faraday Shield • Neon lamp (included) screw terminal of flashlight lamp can cut off the electrostatic radiation • Small radiating plate socket by winding each wire end field from the Tesla Coil. • String or rubber band around each screw terminal. Insert a

Suspend the plate from string socket and second antenna plate. close to the terminal without touching or a rubber band as above. Holding (Connect antenna plate by looping it. Hold a piece of metal behind it to the lamp by its bulb, bring it toward one bare end of wire through the hole draw discharge through the paper. the ball terminal, stop at the point at in the plate). Mount flashlight bulb Move the metal closer so the dis- which the neon gas ionizes. Withdraw into lamp socket. Attach a rubber charge becomes an arc. Observe how the lamp just beyond the point where band or string through hole at end quickly paper is ignited. the neon gas stops glowing. of second plate (through which one This experiment demonstrates how Hold the plate in your other hand wire end is looped) to support this a high temperature is produced when by means of an attached string or plate vertically. This is the plate con- the entire output of the Coil is concen- rubber band. Approach the lamp nected to lamp socket. Operate the trated in an arc discharge. from the opposite side with the lamp Tesla Coil. Holding the plate (known between the plate and ball terminal. as the receiving plate), connect it to Touch one terminal of the lamp with the lamp socket by a rubber band or the plate. Watch the lamp glow when string. Slowly bring toward the other Experiment 17: the insulated conductor - the plate - plate mounted to the top of the Coil. How Air and Metal Compare touches one terminal, despite the fact At a certain point the 10-watt as Conductors of High that the lamp is too far away from lamp will light despite fact there is Frequency Currents ball terminal to ionize on its own. only one wire connecting it to the You Need: Radio and TV antennas oper- Coil. • Piece of Metal. ate this way. They serve as insulated This experiment illustrates the • 7" bare copper wire, included conductors to intercept high fre- dream of Nikola Tesla: to send quency broadcasts from radio and TV electrical power through the air, Operate the Coil with the ball transmitters. without wires, to run factories and terminal in place. With a piece of Experiment 15: homes. Tesla was able to light a bank metal, draw out the discharge as far Transmitting Electrical of 200 lamps at a distance of 20 miles as possible - the maximum separation Power Through Space by plugging one wire into the ground over which a discharge occurs. and connecting the other to an electri- Unplug the Coil. Fasten bare wire without Wires cal receiving aerial. through the small hole in the primary You Need: To transmit electrical power with- terminal post by unscrewing the top • One 2.3 volt flashlight bulb out wires in an actual situation, the knob, inserting the tip of wire (bent • Miniature screw-base lamp socket metallic connection between the sus- into small “L”) through the hole, and • Piece of string or rubber band pended receiving plate and Tesla Coil screwing the knob into place. • Small and large plates in Experiment 15 would be replaced Bend the free wire upward to • 2 lengths of plastic insulated wire, by the ground return through earth. project vertically, about 1" or less l8 " each (included) from the terminal. This is the dis- Experiment 16: charge electrode. Cut 3 foot length of wire (used How Concentrating Output Operate the Coil. Move the free in Experiment 10) in half, yielding Produces High Temperatures end of the discharge electrode away two 18" sections. Strip insulation You Need: from the terminal to draw out the 1/2" from both ends of both pieces. • Piece of metal (coin, key) discharge as far as possible. Move the Remove ball terminal and mount • Sheet of paper wire at its base close to the terminal either small or large plate vertically post. This is the second maximum on threaded stud. Fasten by screwing Warning: separation. Compare the distances terminal onto stud. of maximum length created by these Connect one end of one wire Perform in Area Where two methods. length to ‘primary terminal post” by Fire Can be Promptly Ex- The length of discharge is greater inserting bare end of wire through tinguished using the electrode than the piece small hole located between two black Operate the Coil with the ball of metal. The electrode provides a plastic portions of primary terminal metallic return path for the electrical post. Fasten other end of wire to terminal in place. Approach the current, whereas the metal requires one side of miniature lamp socket. terminal with a piece of metal until that the current pass through the air. Unscrew nut on one of terminals of dis charge occurs in the form of a thin It is impossible to obtain the full socket, wind bare end of other end blue spark. output of the Coil in this experiment, of this wire around screw stud, and Move the metal closer. The dis- due to high resistances offered by replace nut on stud. charge becomes an arc with yellow your body and the air to the flow of Connect second stripped wire flame as you approach the terminal. high frequency electrical currents. between remaining terminal of lamp Take a sheet of paper and hold it

SCIENCE FIRST® | 86475 Gene Lasserre Blvd., Yulee, FL 32097 | 800-875-3214 | www.sciencefirst.com | [email protected] SCIENCE FIRST® | 86475 Gene Lasserre Blvd., Yulee, FL 32097 | 800-875-3214 | www.sciencefirst.com | [email protected] ©2011 - v 1/09 Experiment 18: Experiment 19: Safety Tips and Demonstrating Principles of Transmitting Power with Modulation Radiating Antenna Plates Safety Features: You Need: You Need: This product is designed to be safe • Piece of metal • One 100-200 watt clear glass bulb when used properly. As with any • Large radiating antenna plate, tied electrical appliance, please follow these This experiment illustrates basic • Small antenna plate (included) safety rules: concepts of modulation, which is a • Special lamp socket (included) 1. Plug into grounded (3-prong) 110 condition in which a lower frequency • Small length of wire volt 60 cycle outlet only (house- can supersede a higher one. hold current.) Here the several million cycle per Mount one radiating antenna plate For 10-206, plug into 220 volt second high frequency-voltage pro- vertically to the top of Coil by remov- outlet. duced by the Tesla Coil is modulated ing the ball terminal, fastening the 2. Do not operate in wet or damp by the 60 cycle per second power line radiating antenna plate to the screw locations or outdoors. frequency. stud by placing the small hole in the 3. Check for loose, worn or frayed Operate the Tesla Coil, holding bent ‘L’ of the plate over the stud and wires. Have defective parts re- the piece of metal in your hand. screwing the ball terminal back onto placed. Move the metal up and down the stud to hold the plate in place. 4. While high frequency high volt rapidly in a small arc near the ball This is the transmitting antenna age electricity will not produce a terminal. Observe that discharges are plate. shock, it can cause a burn if taken not continuous but instead occur in Attach the special lamp socket to into your body at one small point the form of individual sparks. the second radiating plate (receiving of contact. Do not come too close The individual sparks occur at a plate) by threading the small length to a discharge; you may be burned. rate of 120 sparks per second - one of wire through both the hole in the Use a piece of metal to take away discharge at each peak of the 60-cycle bent “L” of antenna plate and the hole discharge so it will not build to power frequency. The Tesla Coil gen- in the base of the special lamp socket, unsafe levels of intense heat. erates a few million cycles per sec- then looping the wire over securely. 5. Do not open black enclosure. This ond. Therefore the individual sparks Place the light bulb in the special is a safety guard to ensure your serve to modulate, or bring down to lamp socket. Operate the Tesla Coil. fingers will not come into contact a lower level, the high frequency is Position both antenna plates so with the vibrator or spark gap. generated by the Coil to correspond they are parallel to each other. Hold- Opening black enclosure is a to a 60-cycle per second modulating ing the receiving antenna plate by shock hazard. frequency. the glass of the light bulb, approach 6. Operate the Tesla Coil on a bench Experiment with different speeds the transmitting plate, keeping both or table with a nonmetallic top. as you move the piece of metal up plates parallel. 7. Operate the Tesla Coil under adult and down. You add the dimension Observe the point at which the supervision. of time to your observations because air in the light bulb ionizes. You 8.Your Tesla Coil is NOT designed at each instant the metal occupies a must approach the transmitting plate to be run continuously, due to heat different position with respect to the closely when the plates are parallel to build up in the vibrator (spark terminal. each other. gap). Continuous operation times You may actually be able to make Turn the receiving plate 90° to in excess of 5-10 minutes can individual sparks appear to stand still, transmitting plate and repeat. Com- cause damage to the unit. a condition known as synchronizing. pare distance at which ionization When your speed of movement is occurs. in step with the 60-cycle per second power line frequency, each discharge appears to occur at the same position in space between the moving metal and ball terminal.

mutators in the electric motor. In 1881 close relationship only with his mother, How to Teach with he conceived the rotating magnetic whose death he foretold in a "vision", Tesla Coil: field by 2 or more alternating current making him of interest to believers in Concepts: High frequency elec- out of step with each other; a year later the occult. tricity and generation. Resonance in he built his first actual AC induction In 1899 he was enticed to Colorado electromagnetic field. Reversed polar- motor, using 60 cycle AC which has Springs where he set up his famous ity induction. since been the standard. experimental station with the transmit- Curriculum Fit: Physical Sci- Arriving in 1884 in America with ter he would later claim as his greatest ence, Electricity and Magnetism. Unit: an introduction to Thomas Edison, he invention. He duplicated electrical fire- Moving Charge and Magnets. Grades went to work for the Edison Electric works, conducting power-transmission 11-12 Company. But Edison's heavy invest- experiments and research into ball Subconcepts: Primary/Second- ment in direct electric current, as well lightning. Hearing what was probably ary coil. Mutual inductance. Voltage/ as personality differences, doomed radio waves from the stars, he became current relationship during induc- their relationship. "The War of the Cur- convinced he had received messages tion. Open and closed circuits, short rents" began with mounting hostility, as from outer space. circuiting. Energy conservation in it would take Edison 20 years to admit Ridicule and sensationalism now electromagnetic fields. Transformation his blunder in refusing to recognize dogged his footsteps. Continually sort of electricity to magnetism, vice versa. the importance of alternating current. of funds, his work languished. What Capacitor. Discharge though sparks. Tesla then went to work for George appeared a comeback resulted in the Curriculum Fit: Physical Science/ Westinghouse, to whom he sold the doomed relic of the Wardenclyffe Tow- Electricity and Magnetism. Unit: Elec- 40 patents he had been granted during er erected on Long Island in 1901. This tric Circuits; Energy Transformation. development of the AC motor, an act huge transmitter was intended to be the Static Charge. Grades 6-10 for which he would suffer financially hub of a world system for broadcasting. in later years. It was initially financed by J.P Morgan At this point Tesla seemed at the who withdrew his backing, leaving the peak of his creativity. The ideas ex- tower incomplete. Inventor and pressed in four sensational lectures in In later years, although outwardly 1891 - 2 are considered forerunners of: elegant, Tesla grew bitter, self-serving, Invention theory of cosmic rays; point electron defensive and secretive. Hie continued Nikola Tesla, born in 1856 in a microscope; atom smasher; diathermy; to produce sensational shows in his small village in Yugoslavia, died an modern electric clock, and "Litz" wire, laboratory intended to "dazzle" money American citizen in 1943 after a spec- a stranded cable. It was also the time out of backers. Always, neurotic, he tacular career as inventor, visionary in which he developed his Tesla Coil, became obsessive, gather up sick and and high-society eccentric. A sensation used today in every radio and TV, and wounded pigeons and carrying them of his time, of his time, he combined in which he conducted research several back to his fashionable hotel room to photographic memory, ability to visual- years before the first experiments of tend lovingly. In his office he worked ize complete designs in 3 dimensions, Marconi. in the dark, talking to himself. and excellence at languages and math In 1893 occurred 3 triumphs; in His creativity remained: in 1906, to bequeath to the world his alternating St. Louis he made the first public at age 50, he built his first model of induction motor, high frequency high demonstration of radio communication his bladeless turbine. At 72 he filed voltage generator (Tesla Coil), fluid (later a prolonged, bitter war ensured for patents on his brilliantly designed propulsion turbine and innumerable between Marconi and Tesla over radio vertical takeoff and landing aircraft. patents. patents); alternating current was used The advent of World War II led to his Eccentric even as a child, Tesla to illuminate the Chicago World's Fair; publishing the basic principles of what suffered from inexplicable flashes of and Westinghouse was awarded the would be known as radar. light when he was in stressful situations contract to build the first 2 generators In old age he began to court the and an abnormal sensitivity to noise. using AC at Niagara Falls, New York. press, clamoring for attention with pre- He suffered one apparent nervous Tesla continued to attract media at- dictions for the future. Growing feeble breakdown at age 5 as a reaction to tention. He was an early experimenter in 1942, he worried about his beloved an older brother's death and tow other with X-rays and robots. In 1898 he pigeons, sent a note to Mark Twain - breakdowns later in life. Yet his origi- innocently set up an "earthquake: by dead for 25 years - and finally died on nal mind was also readily apparent. means of vibrations that travelled January 8, 1943 at age 86. 8 months When introduced to the fascinations beneath Manhattan. A bachelor all his later the Supreme Court handed down of electrical machinery by a teacher, life, he attracted the platonic devotion the decision he had felt sure would he immediately conceived the idea of of several women, including J. P Mor- come - that he had invented the radio. dispensing with direct current and com- gan's daughter, but seemed to have a

Tesla Coil Timeline Related Products April 24, 1891. Patent: High Fre- Science First designs and manu- quency transformers factures a wide range of low-cost labs May 20, 1891. Tesla lectures on available from most science education Experiments with High Frequency Cur- distributors. For more information, rents at Columbia College please contact us at 1-800-875-3214. Feb 3, 4 and 19, 1892. Tesla speaks on Experiments with Currents of Ex- 615-3100 and 615-3130 Van de tremely High Frequency before three Graaf Generators - With 200,000 and profession engineering groups. 400,000 volt potentials, respectively. 1893-1899. Various patents con- Raise hair, create lightning, experiment cerning high frequency currents. with St. Elmo's fire. Excellent instructions with many experiments. Our flagship product.

Nikola Tesla patented his air core transformer between June 1891 and November 1891 but the better designs were improvements patented in September of 1896. Two sketches are shown here.

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