The Tesla experiment with the U-shaped bus on a modern element base
Well known experience of Nikola Tesla with a light bulb and a U-shaped copper bus, which is connected through a spark gap to the capacitor and the high voltage source. If in this scheme a light bulb connected to a relatively remote from each other parts of the tire, it will glow. This result could be explained at the level of electrodynamics, if the arrester had worked steadily and with a high enough frequency. It is possible to estimate that the real size of bus, frequency of interrupts of the arrester shall be not less than 500 MHz, but as we know, the maximum frequency of gaps are calculated only kilohertz.
Also, it can be assumed in the second variant, in which the frequency of a spark gap less, and the discharge duration is about 1 NS. But in this case, even if you take fairly large for a spark gap frequency is 10 kHz, the duty cycle will be about 100'000! This means that the bulb 10 W pulsed power spark gap should be about 1 MW, and the reactive capacitor — 1000 kVAr. As is known, the required result is obtained at a much (much) lower values. Therefore, to explain the results of this experiment only with the help of classical physics is impossible.
In this article we will repeat this famous experiment, but on a modern base. Also, let's go a little further and see what will happen with the glowing light bulb if the tire break and the gap to install the condenser.
For this we need a generator of nanosecond pulses, the indicator, bifilar coil, a thick copper wire or bus and the two guide rods from any conductive material.
As GG1, we apply the generator voltage pulses, which, as nagruzki, we will use a bifilar coil (L2 in diagram), for example such. This inclusion allows to achieve the output is quite short, about 140 NS pulses with amplitude In 500-800, depending on the voltage applied to the generator.
Top of L2 is one or more turns of thick copper wire or bus section 3-5 sq. mm. To them are connected two guide rods of conductive material along which can move the indicator IN1. These may be metal tubes, channels or just bare thick wire. On the other end they should be connected with a jumper — for a first experience or is connected through a capacitor Cp for the second.
Indicator IN1 consists of a diode bridge VD1, the output of which is connected to three single-watt led HL1. The input of the bridge is connected to the guide rails instead of the bulb (as in the Tesla experience). The diodes for the bridge, you need to choose high voltage and high frequency, such as UF4007, and the led can be applied like this . To receive the results of the experiment, this indicator will need to move along the guide rails. Depending on the situation, the brightness of its light will change.
As IN1 is also possible to use a low-power incandescent bulb. For example, the author worked well the bulb 26V 0.12 A and automotive — 12V 5W.
The power consumption of the generator GG1 is selected depending on the brightness of the indicator is about 4-7 watts.
Experience No. 1
It is the repetition of the classical experience of Tesla. It ends the guide rails are shorted by jumper. Moving the indicator along the rails we can see it glow, whose brightness will begin to decrease as it approaches the bridge.
Experience No. 2
It ends the guide rails are shorted by the capacitor Cp. Regardless of the type of the used capacitor — inductive or non-inductive — brightness indicator practically does not change when moving along the entire length of the rails. Even when it is connected directly to the terminals of the capacitor Cp, the brightness of the original remains. For experience carrying out applied capacitors of the following brands: К78-28, qoo-3-16kv, FGT-AND-15kV and others. Capacity was varied from 1 nF to 100 nF, which for pulses with a duration of 140 NS is short circuit or the like of the jumper. The results of the experiment also can not be explained by classical electrodynamics in full.