Two charged particles having charge 2.0 × 10–8 C each are joined by an insulating string of length 1m and the system is kept on a smooth horizontal table. Find the tension in the string.
Given,
Charge on each particle, 
Distance between the two charges, 
The tension will adjust such that the net force is zero.
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Formula used:
By Coulomb’s law, the electric force id given by:
Where ϵ0 is the permittivity of free space
q1 and q2 are the magnitude of charges
r is the distance of separation between the charges
(Here, q1 =q2 = q.)
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Putting the values in the above formula, we get
1