The force between two small charged spheres having charges of 2 × 10-7C and 3 × 10-7 C placed 30 cm apart in the air is 6 × 10-3 N.
The force between two charged particles is given by the following equation:
``` F = k * q1 * q2 / r2 ```
where:
- F is the force between the particles (in Newtons)
- k is the Coulomb constant (8.987551787 × 109)
- q1 and q2 are the charges of the particles (in Coulombs)
- r is the distance between the particles (in meters)
In this case, we have:
- q1 = 2 × 10-7 C
- q2 = 3 × 10-7 C
- r = 0.3 m = 30 cm
Plugging these values into the equation, we get:
``` F = (8.987551787 × 109) * (2 × 10-7) * (3 × 10-7) / (0.3)^2 = 6 × 10-3 N ```
Therefore, the force between the two charged spheres is 6 × 10-3 N. This is a repulsive force, since the charges have the same sign.