Friday, 11 May 2018

Capacitance between Earth and Moon


Is there a capacitance between the Earth and the Moon, and if there was enough potential difference, could a discharge strike occur?



Answer



The capacitance between two plates varies as:


$$C = \frac{eA}{d}$$


in which \$d\$ is the distance between the plates, \$A\$ is the area of the plates and \$e\$ is the Coulomb constant. $$e = 8.9 \times 10^{-12}$$ Distance from earth to moon: $$d = 4 \times 10^8\text{ meter}$$ Approximate equivalent earth surface: $$A = (1.28 \times 10^4)^2$$ Therefore, $$C = \frac{8.9 \times 10^{-12} \times 1.64 \times 10^8}{4 \times 10^8} = 2.39 \times 10^{-11} = 10\text{ pF}$$


The numbers were truncated to the nearest the third place.



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