a) What must be the radius of a conducting sphere located in the vacuum so that its capacity is 1 F?
b) Assuming the planet Earth is a perfect sphere of radius equal to 6400 km. What is its capacitance?
The Coulomb Constant in a vacuum is \( k_e=9\times 10^9\;\mathrm{\frac{N.m^2}{C^2}} \).