Learning goal: to understand the nature of electric fields and how to draw field lines. electric field lines are a tool used to visualize electric fields. a field line is drawn beginning at a positive charge and ending at a negative charge. field lines may also appear from the edge of a picture or disappear at the edge of the picture. such lines are said to begin or end at infinity. the field lines are directed so that the electric field at any point is tangent to the field line at that point.

Acommon technique in analysis of scientific data is normalization. the purpose of normalizing data is to eliminate irrelevant constants that can obscure the salient features of the data. the goal of this experiment is to test the hypothesis that the flux of light decreases as the square of the distance from the source. in this case, the absolute value of the voltage measured by the photometer is irrelevant; only the relative value conveys useful information. suppose that in part 2.2.2 of the experiment, students obtain a signal value of 162 mv at a distance of 4 cm and a value of 86 mv at a distance of 5.7 cm. normalize the students' data to the value obtained at 4 cm. (divide the signal value by 162.) then calculate the theoretically expected (normalized) value at 5.7 cm.