Two charges q and 2q are placed along the x -axis in front of a ground...
Problem Statement:Two charges q and 2q are placed along the x-axis in front of a grounded infinite conducting plane as shown in the figure. They are located respectively at a distance of 0.5m and 1.5m from the plane. Find the force acting on the charge q.
Solution:We know that the force acting on a point charge due to another point charge is given by Coulomb's law:
F = (1/4πε
0)(q
1q
2/r
2)
where q
1 and q
2 are the two charges, r is the distance between them and ε
0 is the permittivity of free space.
The force on charge q due to charge 2q is given by:
F
1 = (1/4πε
0)(q(2q)/(1.5-0.5)
2) = (1/4πε
0)(7q
2/2)
Similarly, the force on charge q due to the grounded conducting plane is given by:
F
2 = -2qE
2where E
2 is the electric field due to the grounded conducting plane at the position of charge q. Since the plane is grounded, its potential is zero. Therefore, the potential at the position of charge q due to charge 2q and the grounded plane is:
V = (1/4πε
0)((2q)/(1.5) - q/(0.5)) = (1/4πε
0)(3q/2)
The electric field at the position of charge q is given by:
E = -dV/dx = -3q/(8πε
0)
Therefore, the force on charge q due to the grounded conducting plane is:
F
2 = -2qE
2 = (3q
2/(4πε
0))
Thus, the total force acting on charge q is:
F = F
1 + F
2 = (1/4πε
0)(7q
2/2) + (3q
2/(4πε
0)) = (1/4πε
0)(5q
2/2)
Therefore, the correct option is (d) (1/4πε
0)(q