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Unformatted text preview: 1. 2/2 points All Submissions Notes Web Assign Ch15 HW3 S2010 (Homework) Kiyaniah Tilghman PY 208, section 003M, Spring 2010 Instructor: Keith Weninger Current Score : 17 / 17 Due : Thursday, January 28, 2010 12:30 PM EST About this Assignment Extension Requests Question Points 1 2 3 4 2 2 8 5 Total 17/17 (100.0%) Description Charging and discharging Instructions Reading: Sec. 15.7 The due date for this assignment is past. Your work can be viewed below, but no changes can be made. Question: MI3 15.X.077.alt01 You run your finger along the slick side of a positively charged tape, and then observe that the tape is no longer attracted to your hand. Which of the following are plausible explanation(s) for this observation? Check all that apply. Protons are pulled out of the nuclei of atoms in the tape, and move onto your finger. Electrons from the mobile electron sea in your hand move onto the tape, leaving the tape with a zero (or very small) net charge. Chloride ions (Cl- ) from the salt water on your skin move onto the tape, leaving the tape with a zero (or very small) net charge. Sodium ions (Na + ) from the salt water on your skin move onto the tape, leaving the tape with a zero (or very small) net charge. 2. 2/2 points All Submissions Notes 3. 8/8 points All Submissions Notes Solution or Explanation Negatively charged particles must move onto the tape to give it a net charge of zero. Your hand does not have a mobile electron sea (you are not made of metal). It would require a huge amount of energy to pull a proton out of an atomic nucleus. Question: MI3 15.X.078 You observe that a negatively charged plastic pen repels a charged piece of magic tape. You then observe that the same piece of tape is repelled when brought near a metal sphere. You are wearing rubber soled shoes, and you touch the metal sphere with your hand. After you touch the metal sphere, you observe that the tape is attracted to the metal sphere. Which of the following statements could be true? Check all that apply. Electrons from the sphere moved into the salt water on your skin, where they reacted with sodium ions. After you touched it, the metal sphere was very nearly neutral. Electrons from the sphere traveled through your body into the Earth. Electrons from your hand moved onto the sphere....
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