Other common units can be derived from the base units. Most of the units that are used in electricity are derived ones. Example: Ohm, Volt, Hertz. Exception: Electric Current (ampere)
RoHS, also known as Lead-Free, stands for Restriction of Hazardous Substances. RoHS Directive 2002/95/EC restricts the use of six hazardous materials found in electrical and electronic products. All applicable products in the EU market after July 1, 2006 must pass RoHS compliance. RoHS impacts the entire electronics industry.