### Coulomb's Law activity

LAB ACTIVITY - Relationship between Force and distance

#### Purpose: Find relationship between electric force and distance (radius) from two charges (balloon and rod).

Measurement from video:
Distance (radius) = measurement from end of rod to center of balloon
Force = measurement displacement of center of balloon from center of blue sticky note on wall.

Graphs:
Graph #1 - Radius (on x-axis) vs. Force (on y-axis) - Will not be a linear relationship.

Graph #2 - 1/Distance vs. Force

Graph #3 - 1/Distance^2 vs. Force

Calculations - Take the y = mx + b formula from final graph and re-write to show graph variables and units.

Questions:
1. Compare the slope from your graph to other groups. Why is there a variation?
2. How does this lab relate to the formula for Coulomb's law?
3. What is k and why is it needed in the formula?
4. What is a coulomb of charge?
5. What was the type of relationship found between electrical force and distance?
6. Where else in physics does an "inversed squared" relationship exist?

Conclusion
Standard - Restate purpose, list results (include relationships and mathematical findings), discussion to prove your results and statement of errors (be specific).
Purpose, result, discussion, errors.