Equipotential and Electric Field Mapping Simulation

Theoretical Background

• All charged objects produce electric fields in the space surrounding them. Knowing the shape, direction, and magnitude of an electric field is necessary to determine how a charged particle will interact with the field. 
• Visualization is often helpful when analyzing fields and field forces; however, visualizing a 3-dimensional field can be difficult. A convenient way of representing an electric field is through the use of electric field lines.
• Electric field lines are drawn lines that follow the path of the electric field, originating from a positive charge (or charged object) and terminating at a negative charge (or charged object). 
• The lines never cross, and the density of lines (the number of lines in a given area) represents the magnitude of the field strength. 

These rules are written more formally as: 

• Electric field lines must begin on a positive charge and terminate on a negative charge. 
• The number of electric field lines drawn leaving a positive charge or approaching a negative charge is proportional to the magnitude of the charge. 
• No two electric field lines originating from the same source can cross. 
• Another characteristic of electric field lines is that they always travel perpendicularly across lines of equal electric potential known as equipotential. If a charged particle were to follow one of these lines, its electric energy (or voltage) would not change. 
• In contrast, if a charged particle were to move in the direction of the electric field, across the equipotential of electric potential, work must be done on the particle by the force from the electric field. 
• This relationship between electric field lines and equipotential lines is demonstrated during the electric field mapping simulation.

Principle Work of Electric Field Mapping Simulation

• The concept of field lines is very useful in visualizing electric (and magnetic) fields around charges or charged objects. An electric field line, called a line of force, is an imaginary line drawn such that its direction at any point is the direction of the electric field at that point. The line starts at a positive charge and terminates on a negative charge. 

• By definition all the points on an equipotential line have the same potential. This implies that no work is required to move a charge from one point to another point on the same line and hence equipotential lines are perpendicular to the electric field lines everywhere. 

• So you will draw the equipotential lines first (using voltmeter) and then draw a number of electric field lines going from the positive charge to the negative charge and crossing the equipotential lines at right angles while mapping equipotential lines in the electric field mapping simulation. 

The following are the important properties of electric field maps:

 1. The number of lines crossing an area at right angles is proportional to the strength of the field. In other words where the lines are crowded, the field is strong and where the lines are sparse, the field is weak. 
2. The electric field vector is tangent to the electric field line at each point. 
3. The number of electric field lines leaving a positive charge or approaching a negative charge is proportional to the magnitude of the charge.

• In order to draw the electric field lines, we mount the conductive paper on the corkboard using one of the metal pushpins in each corner. 

• Then, connect the electrodes to the power supply using the supplied connecting wires as shown in Figure 1, which can also be demonstrated using an electric field simulation online or a 3d electric field simulation. 

• After that, we draw the electric field for different patterns using the conductive pen and conductive paper. Some suggested patterns are shown in Figure 2 to illustrate equipotential and electric field mapping.