Electrostatics Question 747
Question: The magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward towards the center of the Earth. This gives the total net surface charge carried by the Earth to be: [Given $ {\varepsilon _{0}}=8.85\times {{10}^{-12}}C^{2}/N-m^{2}, $
$ R _{E}= $
$ 6.37\times 10^{6}m $ ] magnitude of the average electric field normally present in the atmosphere just above the surface of the Earth is about 150 N/C, directed inward
Options:
A) +670kC
B) -670kC
C) -680kC
D) +680kC
Show Answer
Answer:
Correct Answer: C
Solution:
[c] Given, Electric field $ E=150N/C $
Total surface charge carried by earth $ q=? $
According to Gauss’s law.
$ \phi =\frac{q}{{\varepsilon _{0}}}=EA $ or, $ q={\in _{0}}EA={\in _{0}}E\pi r^{2}=8.85\times {{10}^{-12}}\times 150\times $
$ {{(6.37\times 10^{6})}^{2}}. $
As electric field directed inward hence $ q=-680KC $
