oscillate

Universal Words verb [V] 1 ~ (between A and B) (formal) to keep changing from one extreme of feeling or behaviour to another, and back again: Her moods oscillated between depression and elation. 2 (physics) to keep moving from one position to another and back again: Watch how the needle on the dial oscillates. 3 (physics) (of an electric current, radio waves, etc.) to change in strength or direction at regular intervals