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class code: SPS21 teacher: Mr. Elert
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Physics A: Problem Set 1: Electric charge

recommended reading

High Marks: 3:1–3:10
Barron's Let's Review: 8.1–8.5 What is electricity?
physics.info: Electric charge
Wikipedia: Electric charge, Static electricity, Triboelectric effect, Electrostatic induction
Mr. Machado: 01 Introduction to Charge, 03 Charging Methods I - Friction and Conduction, 04 Charging Methods II - Induction, 05 Electroscope

drawing

  1. With the aid of diagrams, show the distribution of charges on two identical uncharged metal spheres in contact during the following experiment.
    1. Bring a negatively charged rod near one of the spheres on the side opposite the point of contact.
    2. Separate the two spheres and remove the rod. What charge does each sphere have?
    3. Touch the two spheres together. What charge does each have?
    4. Repeat the procedure described above, but replace the negatively charged rod with one that is positively charged.
  2. electroscope.pdf
    With the aid of diagrams, show the distribution of charges on an electroscope and the position of its leaves for each of the following scenarios.
    Eight experiments with an electroscope
    initial charge
    of electroscope    		 charge on rod position of rod
    relative to terminal
    a. uncharged positive in contact, then removed
    b. uncharged negative in contact, then removed
    c. uncharged positive near, but not in contact
    d. uncharged negative near, but not in contact
    e. positive positive near, but not in contact
    f. positive negative near, but not in contact
    g. negative positive near, but not in contact
    h. negative negative near, but not in contact
  3. electroscope-hand.pdf
    With the aid of diagrams, show the distribution of charges on an electroscope and the position of its leaves during the following experiment.
    1. Take an uncharged electroscope and place your finger on the terminal.
    2. Bring a negatively charged rod near the terminal.
    3. Move your finger and the charged rod away from the terminal at the same time. What is the charge on the electroscope?
    4. Repeat the procedure described above, but replace the negatively charged rod with one that is positively charged.

writing

  1. Explain how an object that is electrically charged (like a balloon after it has been rubbed on hair) can be attracted to an object that is electrically neutral (like a wall in your home or classroom).
  2. Describe a procedure that could be used to determine the sign of the charge on an object.