Magnetic field lines form in concentric circles around a cylindrical current-carrying conductor, such as a length of wire. The direction of such a magnetic field can be determined by using the "right hand grip rule" (see figure at right). The strength of the magnetic field decreases with distance from the wire. (For an infinite length wire the strength is inversely proportional to the distance.) Bending a current-carrying wire into a loop concentrates the magnetic field inside the loop while weakening it outside. Bending a wire into multiple closely spaced loops to form a coil or "solenoid" enhances this effect. A device so
The Civil Wars: A Tree Is Best Measured When It Is Down The Civil Wars: A Tree Is Best Measured When It Is Down the CIVIL warS: a tree is best measured when it is down is an opera created in the early 1980s by director Robert Wilson to music by Philip Glass, David Byrne, Gavin Bryars and others. The vast five-act work has never been performed whole. Originally, "The Civil Wars" was conceived as a single daylong piece of music theatre to accompany the 1984 Summer Olympics. Six different composers from six different countries were to compose sections of Wilson's text inspired by the American Civil War. After initial premieres in