Resonance
Light, Sound and Waves

Tesla’s earth-shaking brush with the law

Stories from Physics for 11-14 14-16

Whilst testing an electromechanical oscillator, Tesla attached the device to a metal pillar in his building. He observed that the oscillator caused different objects in the room to vibrate. However, the oscillations travelled down the pillar causing nearby buildings to shake, windows to shatter and two police officers to be dispatched to investigate the cause of the disturbance. Having noticed a worrying vibration in the floor and walls of his room, Tesla had just smashed the device with a sledgehammer when the two policemen arrived. He is reported to have politely dismissed the officers by stating:

“Gentlemen, I am sorry. You are just a trifle too late to witness my experiment. I found it necessary to stop it suddenly and unexpectedly and in an unusual way... However, if you will come around this evening I will have another oscillator attached to this platform and each of you can stand on it. You will, I am sure, find it a most interesting and pleasurable experience. Now you must leave, for I have many things to do. Good day, gentlemen.”

He later related to a reporter that, after hiding a similar oscillator in his coat pocket, he placed the device on the steel frame of a building under construction and observed:

“Gradually the trembling increased in intensity and extended throughout the whole great mass of steel. Finally, the structure began to creak and weave, and the steelworkers came to the ground panic-stricken, believing that there had been an earthquake. Rumours spread that the building was about to fall, and the police reserves were called out. Before anything serious happened, I took off the vibrator, put it in my pocket, and went away. But if I had kept it on ten minutes more, I could have laid that building flat in the street. And, with the same vibrator, I could drop Brooklyn Bridge in less than an hour.”

References

Resonance
is a special case of Oscillation
is exhibited by Resonating System
can be analysed using the quantity Resonant Frequency Natural Frequency