Shu Vidyut Sachit Teukay Che

SR No.: 005303
Original Sutra Author: N/A
Author: Mahendramuni
Publisher: Anekant Bharati Prakashan
Publication Year: 2005
Total Pages: 312
Language: Gujarati
Classification: Book_Gujarati
File Size: 13 MB

Page 153

4.
5.
which is of the order of 10 V m to 3 x 104 V m' in upward direction.
6.
Due to this high electric field, air gets ionised and becomes conducting. Towards the end of thunder storm, it allows large amount of negative charges in bursts along narrow pathways from clouds to earth.
In the concluding stages of a storm, there are about 200 flashes or bolts in a storm, each for 2 x 10-3 s. Each bolt carries negative charge to the earth and about-20 C charge is deposited on the earth. There are about 100 bolts of lightning per second through out the world.
The peak current in each bolt of lightning is about-104 C s 1. After each bolt, the thunder storm gets charged again and is ready for next bolt. Thus, thunderstorms make-1800 C of charge to flow from the earth every second, which just counterbalances the steady inflow of + 1800 C of charge to flow from the thunderstorm free regions of the earth.
૧૦૭. એક ગણિતનું ઉદાહરણ આ વાતને વિશેષ સ્પષ્ટ કરે છે, જુઓ Text
book of Physics (Std. XII), Part II, Page 172
"Problem 1: Average surface charge density of the earth's surface is 10 coulomb/meter2. If there exists a potential difference of 400 volts between a certain layer of upper atmosphere above the earth's surface causing a current of 1800 amp (assumed constant) to flow from earth's surface to the atmosphere, how much time will it take earth's surface charge density to become zero?
(Radius of earth = 6400 km)
Surface charge density σ = 109 coulomb/meter2
Surface area of earth 4 π R2.
.. A
51445.5 x 1010 meter2
Total charge Q = σA = 109 x 51445.5 x 1010
= 5.144 x 105 coulomb.
= 1 = 11 = 0
Q
I
= 5.144 x 105
1800
= 0. 2857 × 103
t = 285.7 second.
140