Mr. Kovalls’ Neighborhood

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Electrostatics Lab

(1)  Charge the electroscope by CONDUCTION with the aluminum disk from the charged bakelite electrophorus plate.

    (A) What charge is given to the electroscope?  Explain.                                       

(B) What happens to the leaves?  Explain.                                                                       

                (C)  Complete the diagram.

(2)  Bring the charged disk NEAR the electroscope with the electroscope STILL CHARGED as in #1.

            (A) What happens?

(B)  Explain the behavior of the leaves.

            (C)  Complete the diagram.

(3)  Bring the bakelite plate NEAR the electroscope, with the electroscope STILL CHARGED as in #1.

            (A) What happens? 

(B)  Explain this observation and complete the diagram.

(4)  Discharge the electroscope and then charge it by CONDUCTION with a bakelite rod, after the rod has been

      rubbed on a piece of flannel.

            (A) What charge is given to the electroscope?

    (B)  Explain only the charging of the neutral electroscope.

            (C)  Complete the diagram.

(5)  Bring the charged bakelite rod NEAR the electroscope with the electroscope STILL CHARGED as in #4.

            (A) What happens?

    (B)  Explain this behavior and complete the diagram.

(6) Bring the flannel NEAR the electroscope with the electroscope STILL CHARGED as in #4.

            (A)  What happens?

            (B)  Explain this observation and complete the diagram.

    (C)  What charge is on the flannel?

            (D)  Explain.

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          (7)  Discharge the electroscope by TOUCHING the knob of the electroscope with your finger.

            (A)  What happens?

            (B)  Explain this behavior and complete the diagram.

    (C)  What becomes of the charge on the electroscope?

(8) Use the bakelite rod to charge the electroscope by PERMANENT INDUCTION.

            (A)  What happens to the leaves?

    (B)  Explain this behavior and complete the diagram.

            (C)  What charge is on the electroscope?

  (9) Bring the charged bakelite rod NEAR the electroscope with the electroscope STILL CHARGED by induction as in #8.

    (A)  What happens to the leaves?

            (B)  Explain this behavior and complete the diagram.

  (10) Faraday Ice Pail:  Insulate a metal cup from the ground.  Place a negative charge on the aluminum disk using a Lucite electrophorus plate. Transfer the charge on the aluminum disk to the metal cup making direct contact with the cup’s rim.  Recharge the aluminum disk and place a negative charge on the ball of a neutral pith ball electroscope.

            Bring the charged pith ball NEAR the outer wall of the metal cup.

            (A)  What happens to the ball?

            (B)  Explain this behavior and complete the left diagram.

            Using a swift motion (as demonstrated by the teacher), drop the still charged pith ball into the center of the metal pail, without making contact with any part of the cup.  Slowly, move the charged pith ball around, without making contact with the cup.

            (A)  What happens to the ball?

            (B)  What does the behavior of the ball suggest about any charge residing on the inside surface of the

                   cup?

            (C)  Explain this observation and complete the right diagram.

(11) Bring the charged bakelite rod NEAR a neutral suspended pith ball, but don’t allow it to make contact.

            (A)  What happens to the ball?

       (B)  Explain this observation and complete the diagram.

            (C)  What term describes the behavior of the charged particles?

  (12)  Allow the pith ball in #11 to TOUCH the charged bakelite rod.

            (A)  What happens to the ball?

            (B)  Explain this observation and complete the diagram.

        Bring the charged rod NEAR the charged pith ball.

            (A)  What happens to the ball?

            (B)  Explain this observation and complete the diagram.

(13) Charge a pithball electroscope, by conduction,with the aluminum disk from a charged bakelite electrophorus.  Bring the aluminum disk from a charged Lucite electrophorus NEAR the charged pithball.

            (A)  What do you observe?

  (B)  Explain this observation.

(14) Bring the charged bakelite electrophorus plate NEAR the charged pithball, with is still charged as in #13.

            (A)  What do you observe?

       (B)  Explain this observation.

(15)  Bring the charged Lucite electrophorus plate charged by rubbing it with silk, NEAR the charged pithball, with it still charged as in #13.

            (A)  What do you observe?

            (B)   Explain this observation.

(16)  Bring the charged disk from the Lucite plate electrophorus NEAR the charged pithball, with it still charged as in #13.

       (A)  What do you observe?

            (B)  Explain this observaition.

(17)  Bring the charged bakelite rod NEAR a negatively charged pith ball.  Note the direction of the force exerted on the pith ball by the DIFFERENT PARTS of the rod.

            (A)  What is the direction of the electric field in the different regions of the rod?

            (B)  Diagram and explain.

(18)  Diagram  the direction of the electric field around each of the charged pith balls indicated.

  (19)  Induction Spheres: Place two insulated metallic spheres in contact with one another so that they form a single conductor which can be separated into two parts.  Bring a negatively charged aluminum disk NEAR the left sphere.  With the charged disk still nearby, separate the spheres, then remove the charged rod.  Test the charge on each of the two spheres by placing a negatively charged pith ball near each sphere.  Place the two spheres back together, then retest for the presence of charge on each.  Complete the Diagrams below and explain each step completely.