E = \frac{9 \cdot N m^{2} C^{- 2} \cdot 10^{- 9} C}{(2 \cdot 10^{- 2} m)} = 4, 5 \cdot 10^{4} \frac{N}{C} = 50 \frac{k N}{C}

${E = \mathrm{\frac{9 \cdot Nm^2 C^{-2} \cdot 10^{-9}\, C}{(2 \cdot 10^{-2}\, m)}=4,5 \cdot 10^4\, \frac{N}{C} = 50\, \frac{kN}{C}}}$

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