The watt ( /ˈwɒt/ WOT; symbol: W) is a derived unit of power in the International System of Units (SI), named after the Scottish engineer James Watt (1736–1819). The unit, defined as one joule per second, measures the rate of energy conversion or transfer.

) is the SI derived unit of electrical resistance.

The watt is named after the Scottish scientist James Watt for his contributions to the development of the steam engine. The unit was recognized by the Second Congress of the British Association for the Advancement of Science in 1882. The 11th General Conference on Weights and Measures in 1960 adopted it for the measurement of power into the International System of Units (SI).

The femtowatt is equal to one quadrillionth (10⁻¹⁵) of a watt. Technologically important powers that are measured in femtowatts are typically found in reference(s) to radio and radar receivers. For example, meaningful FM tuner performance figures for sensitivity, quieting and signal-to-noise require that the RF energy applied to the antenna input be specified. These input levels are often stated in dBf (decibels referenced to 1 femtowatt). This is 0.2739 microvolt across a 75 ohm load or 0.5477 microvolt across a 300 ohm load; the specification takes into account the RF input impedance of the tuner.

Charles Edward Anderson "Chuck" Berry (born October 18, 1926) is an American guitarist, singer and songwriter, and one of the pioneers of rock and roll music. With songs such as "Maybellene" (1955), "Roll Over Beethoven" (1956), "Rock and Roll Music" (1957) and "Johnny B. Goode" (1958), Chuck Berry refined and developed rhythm and blues into the major elements that made rock and roll distinctive, with lyrics focusing on teen life and consumerism and utilizing guitar solos and showmanship that would be a major influence on subsequent rock music.

Born into a middle class family in St. Louis, Missouri, Berry had an interest in music from an early age and gave his first public performance at Sumner High School. While still a high school student he served a prison sentence for armed robbery between 1944 and 1947. On his release, Berry settled into married life and worked at an automobile assembly plant. By early 1953, influenced by the guitar riffs and showmanship techniques of blues player T-Bone Walker, he was performing in the evenings with the Johnnie Johnson Trio. His break came when he traveled to Chicago in May 1955, and met Muddy Waters, who suggested he contact Leonard Chess of Chess Records. With Chess he recorded "Maybellene"—Berry's adaptation of the country song "Ida Red"—which sold over a million copies, reaching No. 1 on Billboard's Rhythm and Blues chart. By the end of the 1950s, Berry was an established star with several hit records and film appearances to his name as well as a lucrative touring career. He had also established his own St. Louis-based nightclub, called Berry's Club Bandstand. But in January 1962, Berry was sentenced to three years in prison for offenses under the Mann Act—he had transported a 14-year-old girl across state lines.