Final answer:
To calculate the work done in moving a charge from point A to point B, we need to find the electric potential energy at both points and subtract them.
Step-by-step explanation:
To calculate the work done in moving a charge from point A to point B, we need to find the electric potential energy at both points and subtract them. The electric potential energy of a point charge is given by U = qV, where q is the charge and V is the electric potential.
First, let's calculate the electric potential at point A:
V_A = kσ / r_A, where k is the electrostatic constant (9 x 10^9 Nm²/C²), σ is the surface charge density (40 nC/m²), and r_A is the distance from point A to the sheet of charge.
Now, let's calculate the electric potential at point B:
V_B = kσ / r_B, where r_B is the distance from point B to the sheet of charge.
The work done is then given by W = q(V_B - V_A), where q is the charge being moved. Plugging in the values and doing the calculations, we can find the work done in joules.