even when the paint being disturbed has a lead concentration less than the EPA limit of 0.5%. Illustration 1 is a graph of typical airborne lead levels for common work activities when the paint film that is being damaged contains approximately 0.3% leadâa concentration low enough that the material is exempted from RRP requirements.
Reactance is mathematically symbolized by the letter âXâ and is measured in the unit of ohms (Ï). Impedance is a comprehensive expression of any and all forms of opposition to electron flow, including both resistance and reactance. It is present in all circuits, and in all components.
Measures of Heat. Temperature is a measure of the average translational kinetic energy of the molecules of a system. Heat is commonly expressed in either of two units: the calorie, an older metric unit, and the British thermal unit (Btu), an English unit commonly used in the United States. Scientists express heat in terms of the joule, a unit used for all forms of energy. As heat is added to a substance in the solid state, the molecules of the substance gain kinetic energy and the temperature of the substance rises. The amount of heat needed to raise a unit of mass of the substance one degree of temperature is called the specific heat of the substance.