Final answer:
The problem relates to electric forces and Coulomb's law, and requires using the principle of superposition and the formula for Coulomb's law to find the specific value of charge Q which will result in a net force of zero on charge q.
Step-by-step explanation:
The student is dealing with a physics problem concerning electric forces and Coulomb's law. The charges are arranged linearly with a 4q charge at the 0 position, charge Q at the l/2 position, and charge q at the L position. The question requires finding the value of charge Q for which the resultant electric force on charge q will be zero.
To find the value of Q, we use the principle of superposition, which states that the resultant force acting on any charge is the vector sum of individual forces exerted on it by other charges. These individual forces can be calculated using Coulomb's law, F = k * |q1*q2| / r^2, where F is the force between the charges, q1 and q2 are the magnitudes of the charges, r is the distance between the charges, and k is Coulomb's constant. By setting the force exerted by 4q on q equal to the force exerted by Q on q and solving for Q, we can obtain the required value for Q that makes the net force on q equal to zero.