Physics is a branch of science that studies the natural world and the behavior of matter and energy. The term 'physics unit' refers to the various units of measurement used in physics to quantify physical phenomena. These include the Amp (3 letters), which is the unit of electric current; the Ohm (3 letters), which is the unit of electrical resistance; the ERG (3 letters), which is the unit of energy; the JOULE (5 letters), which is the unit of energy or work; the Fermi (5 letters), which is the unit of length; the Rad (3 letters), which is the unit of absorbed radiation dose; the Dyne (4 letters), which is the unit of force; and the Rhm (3 letters), which is the unit of magnetic flux.