# If the coulomb F between two identical charges is 91.3N, and the distance between the two is 0.446m, what is the magnitude of the charge?

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- MangalLv 48 months ago
Formula to be used:

............ F = (1/4π∈₀) {(Q₁Q₂) / r²}

......................... F = force between charges = 91.3 N

......................... 1/4π∈₀ = coulomb constant = 9x10⁹ Nm²/C²

......................... Q₁ = Q₂ = point charges = not known, to be found = Q (say)

......................... r = distance between charges = 0.446 m

............ 91.3 N = (9x10⁹ Nm²/C²) {(Q² / (0.446 m)²}

=>.............. Q² = (91.3 N) (0.446 m)² / (9x10⁹ Nm²/C²) = 2.028x10⁻¹⁰ C²

=> ............. Q = √(2.028x10⁻¹⁰) C = 4.492x10⁻⁵ C = 44.92 μC (ans)

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- oubaasLv 78 months ago
9*10^9*q^2/0.446^2 = 91.3

q = √0.446^2*91.3/(9*10^9) = 45 μCoulomb

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