Same as law of conservation of energy. Fluid: material that flows, i.e. liquids, gases, and plasmas. Focal length: distance from the focal point to the center of a lens or vertex of a mirror. Focal point: location at which rays parallel to the optical axis of an ideal mirror or lens converge to a point. Forbidden gap: energy values that electrons in a semiconductor or insulator may not have. Force: agent that results in accelerating or deforming an object. Frame of reference: coordinate system used to define motion.
Tuberculosis skin test facts. 1  The tuberculosis skin test is also known as the tuberculin test or PPD test.  The PPD test is used to determine if someone has developed an immune response to the bacterium that causes tuberculosis (TB).
TB diagnostic tests. These are TB tests which can be used to determine if someone has latent TB, which means that they are infected with TB bacteria. There are also TB tests, which when considered alongside other factors, such as whether someone has TB symptoms, can confirm a diagnosis of active TB or TB disease.Even if a person has symptoms, TB is often difficult to diagnose, and is particularly difficult to diagnose rapidly.alse positive results happen with the TB skin test because the person has been infected with a different type of bacteria, rather than the one that causes TB. It can also happen because the person has been vaccinated with the BCG vaccine. This vaccine is widely used in countries with high rates of TB infection.