| Pendulum & Ball (conductor): Attach the pendulum to the Protractor. You can click anywhere in the simulator to attach the pendulum. The ball is connected to the Protractor by a long string that leaves the ball free to swing back and forth. The Protractor records the angle in degrees between the pendulum and the vertical axis. In the pendulum's Properties Box, you can set the ball's charge and either show or not show the Model View. A pendulum ball can exchange charge with a charged sphere through direct contact. The pendulum in the calibration lab has a separate help page.