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[Phys-L] Field Lines and charges



A little something to get us away from politics - I found it amusing - with little deep significance:


Consider a configuration of two point charges of value +q, one placed on the x axis of a standard x-y-z coordinate system at +a and the other at -a. Now look at the electric field vectors - specifically along the y axis.

For any position along the positive y axis the field vector points in the positive y direction. The field magnitude is zero at y = 0, and as y increases, grows and forms a maximum at y = 0.707 a, and then gradually goes to zero as y increases further in value. One could trace a field line starting at y=0, x=0 and follow it along the positive y axis to positive infinity.

For any position along the negative y axis the field vector points in the negative y direction. The field magnitude is zero at y = 0, and as y decreases, grows and forms a maximum at y = -0.707 a, and then gradually goes to zero as y increases further in value. One could trace a field line starting at y=0, x=0 and follow it along the negative y axis to negative infinity.

Here is a pair of field lines that do not follow the usual maxim of starting and stopping on a charge.

Bob at PC