Charges & fields observations

This great learning object from PhET is great tool for discussion in the Physics classroom, as well as a powerful simulation of actual values.

Here are three interesting screen shots that can be used as basis for discussions.

This first picture shows measurements of the electric field strength at 1m and 2m according to the scale.

The field strength at 1 m is given by (9×109NC2/Nm2)(1×10-9C)/(1m)2 =9N/C = 9V/m.

At 2m, having doubled the distance the field strength is only 1/4 as high ~2.25V/m

Field lines are all pointing radially outwards.

Equipotential circles (spheres in three dimensions) around the charge show the electrical potential energy of a positive charge, which will be higher closer to this positive charge.

These show a linear decrease with distance from the point charge.

This picture shows clearly the convergence of field lines between the two like points, as field lines can’t cross.

Between the two charges, the increased field strength pushes the equipotential curves further from the individual charges.

Between the two different charges, the field lines run close to straight from positive to negative. Between these two charges must be a point of 0V.

Feel free to add any other observations in the comments.

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