lab 2
Electric Charge and Coulombs Law
Pre-Lab Questions
Two identical balls are charged to +q and +2q respectively. Draw a free body diagram for the electrostatic force on both balls when they are a distance of 1 m away from each other. Remember vectors have both size (depicted by the length of the arrow) and direction (depicted by the direction the arrow points).
Compare the size of the electrostatic force and gravitational force between two electrons when they are a distance, r, apart. The mass of an electron is 9.11 x 10-31 kg and the charge of an electron is 1.6 x 10-19 C. Show all work.
Hint:
Find the ratio of FE to FG.
Pith balls are small, lightweight objects that can pick up an electric charge. Suppose an experiment is performed and results show that Ball 1 attracts Ball 2. A third ball, Ball 3, is negative and repels Ball 2. What can be concluded about Ball 1? If inconclusive based on the available observations, what additional observations would be necessary in order to draw a conclusion?
Experiment 1: exploring charge with scotch tape
Data Sheet
Table 1: Electric Charge Observations
Procedure
Interacting Pieces
Observations
Part 1
Two pieces on table
Part 2
T1 / B1
T2 / B2
T1 / B2
T2 / B1
T1 / T2
B1 / B2
T1 / Arm Hair
B1 / Arm Hair
Post-Lab Questions
1. Describe the interaction between the top and bottom strips as they relate to electric charge. Did the behavior of the pieces change when the tape was from different sets?
Describe the interaction between two top and two bottom pieces of tape as they relate to electric charge. Is this consistent with the existence of only two types of charge? Use your results to support your answer.
Did the top tape attract your arm hair? Did the bottom tape attract your arm hair? Usually arm hair is neutral; it has equal number positive and negative charges. Use this information to explain your results.
Which pieces of tape are positively charged? Which pieces of tape are negatively charged? Explain your reasoning.
Use your data to create a rule describing how like charges, opposite charges, and neutral bodies interact.
What do you observe about the force of attraction or repulsion when the pieces of tape are closer together and farther apart? Does this change happen gradually or quickly?
eScience Labs, 2018
