When the computer receives a rich signal (high voltage) from the O2 sensor, it leans the fuel mixture to reduce the sensor's reading. When the O2 sensor reading goes lean (low voltage), the computer reverses again making the fuel mixture go rich.
Chemistry and physics are branches of science that both study matter. The difference between the two lies in their scope and approach. Chemists and physicists are trained differently, and they have different professional roles, even when working in a team.
Chemistry is the science that deals with the properties of organic and inorganic substances and their interactions with other organic and inorganic substances. In the study of matter, chemistry also investigates the movement of electrons. Because of the diversity of matter, which is mostly composed of different combinations of atoms, chemists often study how atoms of different chemical elements interact to form molecules and how molecules interact with each other.