Coulombs+Law+Balloons

media type="file" key="CoulombLawlab.mp4" width="300" height="300" media type="file" key="CoulombExplaination.mp4" width="300" height="300"
 * LAB OPTION 1 - Relationship between Force and distance**

**Purpose**: Find relationship between electric force and distance (radius) from the field.
Distance (radius) = measurement from end of rod to center of balloon Force = measurement displacement of center of balloon from center of pink sticky note on wall.
 * Measurement from video**:


 * Data**: Distance(mm) Force(N)

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

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.

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?
 * Questions**:

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.
 * Conclusion**


 * LAB OPTION 2 - Finding charge on a balloon**


 * Purpose** - Determine the number of extra electrons on charged balloon by using Coulombs law.

mass of balloons (kg) length of string (balloon to ceiling) (m) distance between balloons (m) angle between balloons
 * Data** -

In picture - 1 meter = ___mm (Scale for measurements)


 * No graph**

(0) Use scale to determine length of string and distance between balloons for data table and convert mass from grams to kg. 1. Calculate Fg of balloon (Fg = mg; use 9.81 N/kg) 2. Calculate angle from center line to string tension - (angle between balloons / 2) 3. Calculate Fe --> 4. Use Coulombs law to solve for charge (assume both balloons have same charge) 5. Use charge to solve for number of electrons ( 1 coulomb = 6.24 x 10^18 electrons)
 * Calculations**

1. Why did you have to use the picture to measure the distance between the balloons? 2. Compare your number of electrons to other groups. Why do they vary? 3. This number is only excess electrons. How could you figure out total electrons on the balloon? What do you need to know?
 * Questions**

Restate purpose, List results (How many electrons on balloon?) Justify your results. Statement of errors - list 3 and be specific!
 * Conclusion -**