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J. Perelman
"Entertaining physics". Book 2.
Chapter 8. The magnetism. Electricity

HOW MUCH IS LIGHTNING?

In that distant era when the lightning was attributed to "the gods", such a question would have sounded blasphemous. But in our days, when electrical energy is turned into a commodity, which is measured and valued, like any other, the question of what is the cost of lightning, but does need to seem meaningless. The task is to account for the electrical energy required to lightning discharge, and evaluate it at least for the fee of electric lighting.

Here is the calculation. The potential of a lightning discharge is approximately 50 million volts. The maximum current strength is estimated in 200 thousand amperes (it is determined, note by the way, according to the degree of magnetization of the steel rod that current which runs in the winding when the lightning in the lightning rod). Power in watts will get by multiplying the number of volts by the number of amperes; however, it is necessary to consider that, during the discharge, the potential drops to zero; therefore, when calculating the discharge power is necessary to take the average potential, in other words, half of the initial voltage. Have:

power discharge= (50 000 000 * 200 000) / 2,

ie 5 000 000 000 000 watts, or 5 billion kilowatts.

Having such an impressive number of zeros, naturally expect that the cash value of the lightning expressed great figure. However, to get the energy in kilowatt-hours (one that appears in the accounts for electric lighting), you must take time into account. The impact of such a significant power lasts for about the thousandth of a second. During this time used 5 000 000/ (3600 * 1000) ~ 1,400 kilowatt-hours. One kilowatt-hour rate cost to the consumer of the electric current in the 4 cents. From here it is easy to calculate the monetary value of lightning:

1400 * 4 = 5600 kopecks = 56 rubles.

The result is amazing: the lightning, the energy of which is a hundred times more energy shot heavy artillery, would have cost, at the rate of the power plant, only 56 rubles!

It is interesting how modern electrical engineering approached ability to produce lightning. In the laboratories achieved a voltage of up to 10 million volts and the spark length 15 m Distance is not overly significant...

Entertaining physics J. Perelman

 




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