Electrons and Charged Tape

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Use a GOAL experimental approach to design and carry out an experiment to answer the following question using only tape, a ruler, and a protractor:

How many excess electrons are there on the surface of a negatively charged tape?

Use the following information:

• A 3/4" tape 8" long has a mass of 0.24 gm.
• The charge of one electron is 1.6 x 10-19 C.

Guidelines:

• With your group, describe your approach as part of the O step.
• Make a diagram of your setup with vectors.
• Make simplifying assumptions or approximations as needed.

Follow-up:

How does your number compare with the critical density of charge before sparking occurs?

The critical density is 5e-9 C/cm^2.

HW: Write up a group solution to this experimental problems using the GOAL strategy.

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