Question

- The electrostatic force on a small sphere of
charge 0.2microC due to another small sphere of
charge -0.4 uC in air is 0.4 N. The distance
between the two spheres is
a) 4.2 x 10-6 m
b) 4.2 x 10-3 m
c) 1.8 x 10-3m
d) 1.8 10 -6m


plz give correct answer​

Answer 1

Electrostatic force on the first sphere, F= 0.2N

Charge on 1st sphere, q1 = 0.2 μC = 0.2×10‐⁶ C

Charge on the second sphere, q2 = −0.4 μC = −0.4 × 10‐⁶ C

Electrostatic force between the spheres is given by the relation,

$f =k \: \frac{q1 \: q2}{r {}^{2} }$

now putting values .. we get

0.4 = 9×10⁹ × 0.2×10‐⁶ × −0.4 × 10‐⁶

r²

r² = -0.72 × 10⁹+ 10‐¹²

0.4

r² = - 1.8 × 10‐³

hope it helped u..

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