Your instructor will show you how to start the EM field program on the computer.

Select display$/$show grid and then display$/$constrain to grid. Now select file$/$get charges. From the list of files select activity $1.$ With the exception of the letters A$,$ B$,$ C and D your screen should look like:

a$.$ The middle dot represents a positive charge of $8$ arbitrary units.

b$.$ Predict the direction of $E$ at point $A.E_A$ points Explain:

c$.$ Select fields & potentials$/$field vectors. When you click on any point, the electric field vector due to the $+8$ unit charge appears as an arrow.

d$.$ Verify your prediction by clicking on A$.$ If you were incorrect, cross out your prediction and make a correction.

estion $5$ The length of the arrow is proportional to the magnitude of $E.$ We will re the customary units of Newtons per Coulomb and use "grid intervals" on the en for now. What is the length of $E_A$ in terms of grid intervals?

Number of grid intervals for $E_A$