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
What Is a Nation? and continues to be invoked. Political historian Karl Deutsch, in a quote sometimes mistakenly attributed to Renan, said that a nation is "a group of people united by a mistaken view about the past and a hatred of their neighbours". Benedict Anderson's 1983 work Imagined Communities, which states that a nation is an "imagined political community", argues that Renan contradicts himself when he says French people must have forgotten the St. Bartholomew's Day massacre, yet does not explain what it is. In other words, Renan assumes that all his readers will remember the very massacre he says they have forgotten.