UC Santa Cruz Tesla Coil @ SLAC Family Day

1. UC Santa Cruz Tesla Coil@ SLAC Family Day University of California (SC & SD) • Prof. Hartmut Sadrozinski • Drs. Lan Zhang & David Williams • Alan Yang & Ashok Sadrozinski(Sophs) Colorado State University • Dr. Abner Soffer SLAC • Dr. Eduardo do Couto e Silva Independence H.S. San Jose • Mr. Stuart Briber

2. 120 volt Outlet 14,000 volt Transformer 1 million volt Resonance circuit How does the Tesla Coil work? Ask us about details! Voltage starts at 120 ends up at 1 million!

3. Learn about Transformers Power comes out at 14000 Volts Where have you seen this before? Power goes in at 120 Volts Commercial Transformer, hooked up the “wrong way”

4. Transforming Power We hear a lot about conserving Power (turn off lamps, air conditioners, close refrigerator doors...) Electrical Power is just converted wind, water, thermal power It is brought to your neighborhood on high voltage lines Power goes in at 14000 Volts Power comes out At 120 Volts and a transformer brings it down to 120V

5. SLAC GLAST Transformation of Power • Power is used everywhere • At the Stanford Linear Accelerator Center (SLAC): Electricity -> New particles Quarks • Power is tranformed in Space • Black holes explode : • Material -> Light, x-rays, “jets” • SCIPP&SLAC work on GLAST Mission: • discover the most powerful “power plants” in the universe

6. 1 Million Volts! DANGER • Normally you can't see, hear or smell electricity, but the Tesla Coil makes • Bright sparks • Loud crackling noise • The air smell strange (Ozone) BRACE YOURSELF! SAFETY FIRST! • Distance at least 20 ft. • Computers, Gameboys, CD players, telephones to the back of the room – unplugged, switched off! • Hearing aids off, pacemakers out of room!

7. Zorro Drawing lightning with a sword

8. Sparks to grounded sword Wire to safe ground Electricity Moves Through the Air (you knew that, because you use a radio and TV) What about those lights without cords? What is happening with Zorro?

9. Why does Thomas (“Mr. Electricity”) Edison look so grim? • Is it because he preferred DC current?

10. Why does Mr. Nicola (“Sparky”) Tesla look so dapper? • Is it because he preferred AC current?

11. Tesla’s Power Plant at Niagara

12. Nicola Tesla as a Daredevil? • Long Time Exposure makes it safe!

13. Tesla Revival • 271 web sites are dedicated to Nicola Tesla • Join the “Tesla Coil Web Ring”

14. Learn about Resonance That’s how a swing works: A kick at the right moment builds up and gets you sky-high! In the Tesla “swing”, the kick is supplied by the AC electrical current moving back and forth

15. Electricity in Air Lightning Jacob’s Ladder Corona Tesla Sparks are all related. Principle: Air is made of very small bodies called “molecules”. When they are broken apart (“ionized”), they become charged and can conduct a current like an electrical wire. If there is a large current, it heats up the air and makes light (like in your toaster!). Thus, the sparks, flames etc are direct evidence for the model of atoms!

16. + + + + + + + + + + + + + + – – – – – – – – – – – – – – – – – – – – – – – – – – + – + – + + + + – – + + + – – + + + – + + – + – – + + + + + + – – – – + – + + + + + + + + + + + + + + + + + + + + + + + + How lightning works Ground is safe!

17. + + + + + + + + + + + + + + – – – – – – – – – – – – – + + + + + Safest place during a lightning storm is in a plane or car because it is a Faraday Cage The Faraday Cage Planes are close to the clouds and away from safe ground. Why aren’t they in grave danger from lightning? Answer: They form a “Faraday Cage” -- that is, they are surrounded by metal. Electricity flows around the outside of the metal, and anything inside is safe!

18. Chicken Wire = Mostly Holes

19. Meet the Fighting Knight Who is afraid of Lightning? Fighting Lightning Bolt to the Head Sparks from the Feet

20. Is the Mystery Knight OK? Let’s check! The armored suit is safe! • It's a Faraday Cage – no electric field allowed inside. Invisible current 1 Million Volts Electrical current flows on the OUTSIDE of a metal! Visible sparks Visible sparks Ground

21. Fysiks is Phun! Questions? Ask after the show, e-mail, visit… You find our coordinates on the web http://scipp.ucsc.edu

22. Say “Good bye” to Daniel Greenhouse, the brain behind the sparks He was an undergraduate at UC Santa Cruz. Thanks to our hosts: • All you young scientists • Ms. Teresa Troxel and her gang • Knight Steve Williams http://scipp.ucsc.edu

23. E=VJ/d R 14kV off: on: RJ R RJ R RJ>>R -> VJ>>VR RJ<<R I=V/(RJ+R) I=0 High voltage sparks I: Jacob’s ladder

24. 110 VAC -> >=14kV • C gets charged • high V across S • virtual capacitor (T -> ground) • resonant circuit (S2,T) • energy transfer • voltage gain : • power transfer/sparks at w1 (10-100 MHz) • S breaks down • C discharges through P2 • resonant circuit (S,C,P2) High voltage sparks II: Tesla coil T primary transformer S C P2 S2 secondary transformer

25. T primary transformer S C P2 S2 secondary transformer

26. Transformer 101: Energy (Power ) (at best! - heat, sound, motion!) conserved  I*V constant Primary (n1) and secondary (n2) share the Magnetic Flux  (use iron core!)  V1  n1*d/dt  V2  n2*d/dt  n2/n1* V1

27. Resonance That’s how a swing works: Match Resonance Frequency and In-Phase In the Tesla “swing”, the kick is supplied by the Primary Coil, so it has to be tuned to the secondary circuit to be in resonance