What is the magnitude of the force of a +25 microCoulomb charge exerts on a +2.5 miliCoulomb charge 28 cm away?

7.175 N

Explanation:

From coulomb's law of electrostatics,

F = kQq/r² Equation 1

Where F = magnitude of the force, M = first Charge, q = second Charge, r = distance between the charges and k = coulomb's constant

Given: Q = +25 micro-Coulomb = + 25×10⁻⁶ C, q = +2.5 micro-coulomb = +2.5×10⁻⁶ C, r = 28 cm = 0.28 m.

Constant: k = 9×10⁹ Nm²/C²

Substitute these values into equation 1

F = 9×10⁹(25×10⁻⁶)(2.5×10⁻⁶)/ 0.28²

F = 562.5×10⁻³/0.0784

F = 7.175 N

the device is called “ rocket engine”