Achild on a playground swing makes a complete to-and-fro swing each 2 seconds. the period is: 0.5 seconds 1 second 2 seconds

When is a current produced? when the terminals of an electrochemical cell are connected by a wire if the electric circuit is opened in an electrochemical cell if the electrolyte is removed from an electrochemical cell when the electrodes are reversed in an electrochemical cell