In a demonstration a student drops a neutral polystyrene sphere toward the top of the dome of a negatively charged Vann de Graaff generator. The polystyrene sphere is coated with an electrically conductive surface.

Observation 1: the student initially observes the sphere fall toward the Van de Graaff generator.

Observation 2: the student next observes the sphere touch the top of the generator and move upward.

Use the concepts associated with electric field, electric force, and charging by induction and charging by conduction to analyze the demonstration and observations given above.

Qi: In your analysis of the demonstration above, draw and label the field lines that show the shape and direction of the electric field around the dome of the Van de Graaff generator.

Q2: In your analysis of observation 1, describe the rearrangements of charge that occurs on the neutral sphere as it falls toward to top of the Van de Graaff generator, and explain why this occurs?

Q3: In your analysis of observation 1, predict the change in magnitude of the acceleration of the neutral sphere as it falls toward the top of the Van de Graaff generator, and justify your prediction with appropriate formulas.

Q4: In your analysis of observation 2, explain why the sphere moves up and away from the Van de Graaff generator?