Question

A physics student is doing experiments with a Van de Graff generator that has a positively charged dome. A small balloon is held near the generator and it is deflected toward the generator and reaches equilibrium at a point 40° from the vertical when the separation is 15 cm. The mass of the balloon is 50 grams.

a) Is the balloon positively or negatively charged? Justify your answer.

b) Draw a free-body force diagram of the forces acting on the balloon while it is stationary.

c) Calculate the magnitude of the electric force.

d) Would the angle of deflection from the vertical increase, decrease, or stay the same if the balloon was moved to a separation distance of 7.5 cm?

e) The student allows the balloon to touch the dome of the Van de Graff generator and observes that the balloon is now repelled by the dome of the Van de Graff generator. Explain what happened when the balloon was in contact with the dome.

Answer 1