Two charges +2 coulomb each are placed 2 m apart in vacuum, force

Two charges +2 coulomb each are placed 2 m apart in vacuum, force
| Two charges +2 coulomb each are placed 2 m apart in vacuum, force of repulsion between them will be:

A. 9 &times; 10<sup>9</sup> N

B. 9 &times; 10<sup>9</sup> dyne

C. 9 &times; 10<sup>9</sup> kgf

D. 9 &times; 10<sup>9</sup> kN

Please scroll down to see the correct answer and solution guide.

Right Answer is: A

SOLUTION

CONCEPT:

  • Coulomb’s law: When two charged particles of charges q1 and q2 are separated by a distance r from each other then the electrostatic force between them is directly proportional to the multiplication of charges of two particles and inversely proportional to the square of the distance between them.

Force (F) ∝ q1 × q2

\(F \propto \frac{1}{{{r^2}}}\)

\(F = K\frac{{{q_1} \times {q_2}}}{{{r^2}}}\)

Where K is a constant = 9 × 109 Nm2/C2

CALCULATION:

Given that:

q1 = 2 C and q2 = 2 C, r = 2 m

The force exerted by one charge q1 on another charge q2 is given by Coulomb's law:

\(F = \frac{1}{{4\pi {_0}}}\frac{{q_1 q_2}}{{{r^2}}}\;\)where \(\frac{1}{{4\pi {_0}}} = 9 \times {10^9}\frac{{N{m^2}}}{{{C^2}}}$\)

\(F = 9 \times {10^9} \times \frac{{2 \times 2}}{{{2^2}}} = 9 \times {10^9}N\)

So option 1 is correct.