Name: ______
Date: ______

INDUCTION LAB: METAL LEAF ELECTROSCOPE

Purpose: To charge a metal leaf electroscope by induction.

Materials and Methods: (If at any time the leaves stick together, touch the metal ball with your fingers and use a pencil to GENTLY separate the leaves)

  1. Observe the metal leaves of a neutral electroscope noting their position.
    (Make a sketch of the electroscope and leave room to add labels and charges later)
  2. Approach the metal ball of the uncharged electroscope with a negatively charged ebonite rod (do not touch the electroscope) and observe the leaves.
    (Make a sketch of the electroscope with the rod close and leave room to add labels and charges later)
  3. Repeat with a positively charged glass rod.
    (Make a sketch of the electroscope with the rod close and leave room to add labels and charges later)
  4. Connect one end of an insulated wire to the neck of the electroscope just under the metal ball. Connect the other end of the wire to a metal water tap or gas valve. Bring a negatively charged ebonite rod near (do not touch) the ball of the electroscope. While the rod is still very close to the electroscope, remove the wire from the water tap or gas valve without touching any part of the electroscope. After you have done this, remove the charged rod and observe the leaves.
    (Make a sketch of the electroscope with the wire still attached but showing the final position of the leaves once the rod has been removed and leave room to add labels and charges later)

Observations: (Attach your large, pencil sketches)

Questions: (Answer in full sentence on separate page)

  1. Explain what happened in step 2 in terms of the movement of electrons. Explain why the leaves did what they did.
  2. What kind of charge was induced on the metal-leaf electroscope by the ebonite rod?
  3. Explain what happened in step 3 in terms of the movement of electrons. Explain why the leaves did what they did.
  4. What kind of charge was induced on the metal-leaf electroscope by the glass rod?
  5. Explain what happened in step 4 in terms of the movement of electrons. Explain why the leaves did what they did.
  6. Write a summary statement identifying the kind of charge (positive or negative) transferred to an object when it is charged by induction by an ebonite rod and by a glass rod.