Electrostatic Images

                                                            

Conductor Simulation

Charge Simulation

Description

The simulation on the left represents a positive charge (+q) at the position (x,y)=(d,d) near two infinite grounded conducting sheets. The animation on the right depicts a similar situation without the conductor present. The rectangles are there for your reference only.

Question

Use the animation on the right to place charge(s) where they belong to make the field on the right match the field on the left for x>0, y>0 (the region where the +q is located). Assuming you could do this, where are the charge(s)? 

   


Instructor Resources

Answer: There are three charges needed. One +q charge at (x,y)=(–d,-d) and two –q charges at(x,y)=(d,-d) and (x,y)=(–d,d), respectively. The electric potential on the conductor will not be zero otherwise. This is another example of the method of images from electrostatics. Again, the electric field is indeed different outside of the region of interest. This is a good in class warm up for the out of class calculation of the electric potential and electric field of this configuration since the instructor knows the students’ starting point for the calculation.
Script Author: Mario Belloni