Question

If two opposite electric charge having same magnitude are 10 cm away from each other they experience 0.9 N attractive force then the magnitude of electric charge will be
a.1uC b.1nC c.1pC d 1.mC

Answer 1

The magnitude of electric charge is option a. 1uC or 10^-6 C

-The solution is straight forward application of Coulomb's force law,

-here, F = -0.9 N (negative because its attractive)

          r = 10 cm = 0.1 m

          K = 9 * 10^9 N.m^2/C^2 (assuming the set-up is in vacuum or air)

-Let the two opposite charges be Q and -Q

-Then according Coulomb's law, F = K.(Q).(-Q) / r^2

putting all the values in the equation, we find Q = 10^-6 C or Q=1uC