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Physics Education Technology - University of Colorado, Boulder

HTML5 John Travoltage Simulation

JohnTravoltage Sim

Try the newly published tablet-compatible John Travoltage simulation.

Make sparks fly with John Travoltage. Wiggle Johnnie’s foot and he picks up charges from the carpet. Bring his hand close to the door knob and get rid of the excess charge.

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Nov 26


4 Comments | Add your comment ↓

  1. Uh oh, the sim’s science behavior has changed.

    I like the fact that the sound effects have been left intact, but I would like to see previous discharge behaviors restored:

    PREVIOUS SIM BEHAVIOR (not available in the HTML5 version)
    1. A fully charged John (hand away from knob) has his hand moved until a discharge begins. The hand can then be pointed away from the knob while the discharge continues, showing the higher conductivity of ionized air in the discharge path. The discharge will not initiate when the hand is pointed away from the door, but it will continue across that distance when the path is more conductive. Yum!

    2. While that long-stream discharge continues, the foot can be rubbed to replenish John’s charge. The discharge can be allowed to continue for many, many seconds. Okay, that one’s just a fun additional challenge for students to puzzle through.

    The new HTML5 version stops the discharge in progress if the hand is pointed away from the knob. Maximum-distance-maximum-time discharges are no longer possible.

    The screenshot image shown on my “Greased Lightning” activity is not possible in the HTML5 version right now.

  2. 3. The previous version also had a non-zero minimum gap distance between John’s hand and the knob. This required a certain threshold of static charge to be built up on John before a discharge would occur. The new version will discharge immediately upon any charge being placed on John. Once again, I prefer the geometry and behavior of the previous version. Please restore.

    On the upside, I do appreciate that John cannot discharge from his (relatively insulated) foot. Thanks for maintaining that behavior.

    • Thanks for the comments. We have forwarded this to so our developers can respond to your feedback!

    • Thank you so much for your thoughtful comments on the behavior of the HTML5 version of John Travoltage. We have posted a new HTML5 version that addresses some of your concerns with the change of behavior of the sim.

      As a team we felt that allowing John to discharge with his finger at the maximum distance was too unrealistic. So you can still move the hand while it is discharging, just not to maximum distance. The physics is a bit more accurate. The sim shows that the discharge continues if you move John’s hand (showing the higher conductivity of air), but it is does break off after a certain threshold.

      You should also be able to get a discharge going and continuing by rubbing John’s foot (and keeping the finger close to the discharge point). Finally, as you requested we have added a non-zero minimum gap distance between John’s hand and the knob.

      The PhET team sincerely appreciates your use of our sims and your feedback!

      Ariel J. Paul
      Development Coordinator

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